GIFT  OF 


GIFT  OF 


MECHANICAL    ACHIEVEMENTS    OF    THE    XIX.    CENTURY. 


STE  VEINS' 

Mechanical  Catechism 

FOR 

STATIONARY    AND     MARINE     ENGINEERS,    FIREMEN 

ELECTRICIANS,  MOTOR-MEN,  ICE-MACHINE 

MEN  AND  MECHANICS  IN  GENERAL 

PRACTICAL  KNOWLEDGE 

IN    EVERY    BRANCH    OF    MECHANICAL    INDUSTRY 

Full  Information  on  Water,  Steam,  Fire,  Smoke,  Electricity,  Horse- 
Power,  Refrigeration,  Liquid  Air.  Exact  Description  of,  and  Directions 
for  the  Care  of    Boilers,    Grates,   Engines,  Slide  Valve,  Safety 
Valves,  Injectors,  Pumps,  Steam  Gauges,  Lubricators,  Eccen- 
tric, Link  Motion,  Indicator,  Ammonia  Compressor.  Brine  and 
Direct  Expansion  Systems,  Lathe,  Tools,  Dynamo,  Batteries, 
Parallel  and  Series  Wiring,  Three- Wire  System,  Motors, 
Controller,   Electric    Heating,  House  Wiring,  Traction 
Engine.  Thorough  Instruction  in  Calculation  of  Horse- 
Power,  Pulley-Speed,  Lathe-Gearing.  Square  Root. 
Leverage,  Tensile  Strength,  etc.     Introduction  to 
Algebra.      Systematic    descriptions     alternate 
with  elaborate  sets  of  Questions  and  An- 
swers in  plainest  English.  Numerous  tables 
and   original   diagrams  make  the    book 
interesting  as  well  as  instructive.        .. 
Valuable  Recipes  and  Hints  for  all      rff^ 
sorts  of  Emergencies,  many  of  them 
especially  selected  for  this  work. 

OVER    240    SECTIONAL    CUTS    AND     ILLUSTRATIONS 

BY  . 

H.    G.    STEVENS,    M.E.E. 


Copyright  1899,  by  WM.  H. 


CHICAGO 
LAIRD    &    LEE 


TABLE  OF  CONTENTS 

The  Alphabetical  Index,  pages  5-9,  gives  subjects  in  detail. 


PAGE 

WATER 11 

STEAM*. 16 

COMBUSTION  AND  FIRING..    19 

Locomotive  firing 29 

BOILERS 33 

Rivets,  Braces  and  Stays    33 

Plant  appliances 38 

Boiler  explosions 46 

.Running  a  boiler 49 

Steam  heating 52 

Smoke  and  chimney 53 

Brickwork 54 

Boiler  testing 56 

Boiler  horse-power 57 

Feed  water  heater 59 

Tensile  strength 60 

SAFETY  VALVES 62 

INJECTORS   69 

FEED  PUMPS 73 

STEAM  GAUGES 89 

LUBRICATORS... 91 

THE  ENGINE 96 

Valve  setting 97 

Reversing 100 

Lead  and  lap 102 

Compound  engines 104 

Corliss    electric    engine 

stop 107 

Hot  air  engine 109 

Condensers 112 

The  eccentric 116 

Dead  centers 118 

Lining  the  engine 120 

Automatic  governors 124 

Balanced  slide  valve  —  133 
Corliss  engine  and  gear.  135 

Vacuum  dash  pot 140 

Review 141 

Link  motion 144 

HORSEPOWER 146 

INDICATOR 154 

Pantograph 160 

Review    162 


PAGE 

COMPRESSED    NON-VIB'R. 
AIR  ENGINE 166 

MISCELLANEOUS  questions 

and  answers 169 

Mea.surements  and   cal- 
culations     175 

MECHANICAL   REFRIGER- 
ATION   180 

Ammonia 182 

Methods  of  refrigeration  185 

Water  examinations 195 

Direct  expansion  system  197 

Ammonia  tests,  etc 211 

Review 219 

LIQUID  AIR 223 

Liquid  hydrogen 225 

THE  MACHINE  SHOP 226 

The  lathe 228 

Twist  drill  grinding 231 

Polygonal  nuts 233 

RULES    AND    STANDARD 
NUMBERS 234 

GENERAL     USEFUL 
KNOWLEDGE 242 

ELECTRICITY 249 

Dynamo     and     attach- 
ments  ?67 

Varieties  of  dynamo 275 

Management 279 

Repairs 287 

Measurements 290 

Motors 297 

Controllers    301 

Electric  locomotive 304 

Electric  heating 306 

Motor  connections 308 

Electric  wiring 309 

THE  ELEMENTS  OF  ALGE- 
BRA   318 

THE  TRACTION  ENGINE..  324 

THE  HAY  STACKER 332 

JOURNAL    Box    BABBITT- 
ING   335 


INTRODUCTION 

Almost  every  day  some  new  device  is  invented 
for  saving  labor  or  fuel  or  other  material.  Where 
so  many  brains,  scientifically  trained,  and  so  many 
thousands  of  practiced  eyes  and  hands  combine  to 
make  human  life  more  comfortable,  by  shifting  an 
ever  larger  portion  of  the  hard  labor  to  the  shoul- 
ders of  Nature's  hidden  forces,  it  is  not  strange 
that  the  engineer  and  machinist  finds  greater  and 
greater  demands  made  on  his  intelligence  and 
experience. 

A  widely-known  machinist  delights  in  repeating 
to  his  friends  his  account  of  a  little  incident  that 
•will  illustrate  our  point.  He  happened  to  enter  the 
office  of  a  large  factory,  where  one  of  the  firm 
jumped  at  him  and  hustled  him  into  the  engine- 
room,  where  the  men  tending  the  machinery  were 
standing  idle  and  puzzled.  Something  was  wrong ! 
"Start  her  up,"  said  the  proprietor.  The  big 
engine  made  two  or  three  revolutions,  giving  a 
thump  at  each  turn  as  if  the  fly  wheel  was  about 
to  goto  pieces.  "Stop  her!"  the  machinist  said, 
took  the  key  of  shaft  and  fly-wheel  out,  filed  it 
down  one  s&ty-fourth  of  an  inch,  and  then  drove  it 
in  place  again — and  she  started  up  without  a 
thump.  "Well,  I  declare,"  said  the  proprietor, 
"how  much  do  I  owe  you?"  "Twenty-five  dollars 
and  fifty  cents."  "What's  that,  sir — $25.50  for 
twenty  minutes  of  your  time?"  "No,  sir ;  50  cents 
for  my  time  and  $25  for  knowing  just  what  to  do. 
It's  worth  that  much  to  you,  I  dare  say,  to  get 
your  men  to  work,  isn't  it?"  The  money  was 
cheerfully  paid. 

It's  the  PRACTICAL  KNOWLEDGE  that  tells ;  and 
to  aid  engineers  and  mechanics  in  general  to  do 
intelligent  wor^  is,  the-desrj^  and  aim  of 

C:  O  J.  O  V  1>         THE  AUTHOR. 


LIST  OF  ILLUSTRATIONS 


PAGE 

Cross  Compound  Engine. .    10 

Ice  Plant 10 

Smoke  prevention 25 

Riveting 33,34,35 

Gusset  stay 36 

Steam  fittings 39 

Globe  valve 40 

Water  column 42 

Safety  alarm 43 

Boiler  water  line 45 

Straightway  valve 50 

Boiler  setting 54,  55 

Safety  Pop  and  Muffler.  .63,  64 

Safety  valve  (lever) 68 

Injector 70 

Duplex  pump 76 

Check  and  gate  valves. .  .82,  83 

Artesian  pump 84 

Pump  governor 85 

Deep  well  pump  and  plun- 
ger  

Steam  Gauge  

Double    and    Triple   feed 

lubricators 91,93 

Common  slide  valve  and 

movements 96,  98,  100 

Tandem  Comp'd  Engine..  106 
Corliss  electric  engine  stop  108 

Hot  air  engine 110 

Connecting  rod  and  oilers 

Ill,  112 

Concentric  and  eccentric. .  116 
Direct   and     indirect   mo- 
tion    117 

Slotted  stick 121 

Engine  lining .   ..122 

Automatic  governors..  125,  130 

Balanced  slide  valve 133,  134 

Corliss   valve    movements 

135,  136,  137 

Corliss  cut-off  gear 138 

Vacuum  dash  pot 140 

Ivink  motion 144 

Indicator 154,155 

Indicator    chart   and   dia- 
grams  156,  158,  159,  160 

Pantograph 161 

Air  engine '. 167 

Crank  pin  travel 169,  170 

Dead  center  points 172 


PAGE 

Ice  machine 184,  186 

Freezing  tank 192 

Ice  can  dumps 194 

Compressor  valve 197 

Gas  compressors 199,  201 

Ammonia  liquefier 203 

Valves  and  fittings 207 

Bye  pass  valve 208 

Ammonia  testing 211 

Engineer's    and    machin- 
ist's tools 226,227 

Lathe  and  tools 228,  230 

Twist  drill  grinding...  .231,  232 

Area  of  circle. . .   234 

Ventilation 243 

Arc  lamp 255 

Incandescent  lamp 261 

Dynamo 268 

Storage  batteries 271,  272 

Rheostat 272 

Transformer    and    brush 

pointer 273 

Alternating  dynamo 276 

Generator  panel 279 

Feeder  panel 280 

Chemical  meter 295 

Stationary  motor 297 

Carbon  Brush  Holders 298 

Third  rail  motor  trucks. . .  299 
Street  car  motor  suspen- 
sion and  motor  truck. 300,  301 

Electric  car  controllers 302 

Electric  locomotive 304 

Electric  Heating  and  Cook- 
ing      307 

Stationary  motor  connec- 
tions    308 

Wire  joints 314 

Traction  engine 324 

Coal  and  water  tank 325 

Curve  turning  device 325 

Compensating  gear 326 

Friction  clutch  fly  wheel. .  326 

Cross  head 327 

Tandem  compound  cylin- 
ders  329 

Single  eccentric  reversing  330 

Reversing  rack 331 

Hay  stacker  gearing. . .  332,  333 
Hay  stacker. —  334 


ALPHABETICAL  INDEX 


NOTE  :  For  Electrical  Terms  see,  also,  Dictionary,  page  253. 


PAGE 

Absorption  method,  ice.. . .  185 

Accidents  by  shafting 245 

Accumu!ator 271 

Air,  a  compound 13 

'    chamber,  Duty  of. ...     83 
'    Compressed— engine..  166 

'    in  combustion 19 

Liquid 223 

needed  for  fire 23 

spaces  in  grates 20 

Weight  of 13 

Alcohol  expansion 18 

Algebra,  Elements  of. 318 

Alternating  current 252 

Ammonia 182 

"         Boiling  points  of  210 

Charging 917 

"         compressors 184 

"         condenser  ...188,  202 

Discharging 219 

"         pump  valve 197 

tests 211 

' '         valve  and  fittings  207 

Ampere 291 

Ampere's  Rule 252 

Appliances  of  steamplant.     38 

Area  of  circles 235 

Artesian  pump 84 

Atmosphere,  Weight  of. . .     14 

Automatic  gov.,  side  crank  124 

self-contained.  129 

Babbitting  a  journal 335 

Balanced  slide  valve 133 

Ball  turning 229 

Band  saw  mending 168 

Barometer 14 

Battery,  Electric 271 

"        of  boilers bl 

Belting,  Cleaning  of.   248 

"        horsepower 152 

Boiler,  The 33 

construction 45 

explosions 46 

How  to  clean 49 

"        Safe — pressure  .   . .  176 

"        setting 40,54 

"       testing 56 


PAGE 

Boilers,  Battefy  of. 51 

Boiling,  Definition  of 18 

Boiling  points  of  ammonia  210 

Braces 35 

Brine  solutions,  Table  of  .  195 

"      system 190 

Brushes,  Motor 298 

Brush  holder 273 

B.  T.  U 293 

Bye  pass  valve 207 

Calculations,  Engine 175 

of  coal  in  bin.  248 
Pulley  speed..  239 
Stay  and  bolt.  38 

Capacity  of  pump 74 

Carbonic  acid 13 

Care  of  electric  plant 284 

Casing  for  electric  wire. . .  316 
Cell,  Daniell 274 

"  Gravity 274 

Cement  for  steam  pipes . . .  222 

Charging  ice  machine 217 

Check  valve 81,83 

Chimney 53 

Circuit,  Arrangement  of. .  314 

11  Short 312 

Cleaning  by  steam 247 

belts 248 

/  "  rusty  steel 247 

Clearance 176 

Closed  coil 276 

Clutch,  Friction 326 

Coal,  Decomposition  of. . .  21 

'•  How  it  burns 22 

Coal-bin  calculations  .* . .  248 
Cold  storage  temperature.  206 

Color  of  flames 20 

Combustion,  Perfect 19 

Commutator 270 

Compensating  Gear. 325 

Compound  engines 104,  328 

Compressed  air  engine...  166 
Compression  method,  ice..  187 

Compressor,  Ammonia 197 

Condensation,  Ammonia..  188 
Condensers,  Ammonia.  188,  202 
Jet 114 


INDEX 


Condensers,  Open-air 204 

Steam 112 

Surface 113 

Conductivity 310 

Connecting  rod 122 

Connections,  Electric 314 

Constant  potential  service.  278 

Continuous  current 252 

Controller 301 

Converter 273 

Cooking,  E)lectric I . 

Corliss  electric  stop 107 

Engine   135 

Coulomb 291 

Crankpin    and    crosshead 

travel 169 

Crosshead  at  dead  center. .  172 

of  engine 327 

Current,  Alternating 252 

"         Continuous 252 

"         Multiphase  252 

Cut-out,  Electric 316 

Cylinder  dimensions 328 

Daniellcell 274 

Dash  pot 141 

Dead  center 118 

Deep  well  plunger 87 

"         "     pump 87 

Diagram,  Indicator 15ti 

Dictionary.  Electrical 253 

Differential  gear 325 

Dimensions  of  cylinders. .  328 
Direct  expansion  system. .  190 
Discharging  Ammonia 

Pump  219 

Distribution,  Electric 314 

Duplex  gauge     90 

Dyne 290 

Dynamo  and  its  parts  267 

Care  of. 279 

"         Efficiency  of 293 

Repairs  of. 287 

Running  a 283 

Varieties  of 275 

Eccentric 116 

How  to  set  an. ..  117 

rod 9?' 

Single-revers- 
ing    100,  330 

Efficiency  of  Dynamo 293 

Electric  locomotive 304 

4 '      heating  and  cook- 
ing   306 

11      measurements —  290 


Electric  wiring 309 

Electricity,  Chemical  and 

thermal 251 

"          Current    and 

statical 250 

Frictional  and 

voltaic 250 

Positive      and 
negative ....  249 

Elements  of  Algebra 318 

Engine,  The 96 

Compound 104 

with 

single  valve. . . .  328 
Compressed  air  .  166 

Corliss 135 

stop,  Corliss  elec.  107 
Cross  compound  105 

crosshead 327 

Electric   304 

Hot-air  pump'g.  109 

Lining 120 

measurements..  175 

pounding 119 

Receiver ..  105 

striking  points..  122 
Tandem     com- 
pound   105,  328 

Traction 324 

Erg 290 

Expansion,  Ammonia 188 

system,  Direct  190 
Explosion  of  boilers 46 

Feed  of  boilers 43 

' '     regulation 57 

Fire,  Care  of 25 

engine 83 

Firing 19 

Locomotive 29 

Stages  of 20 

Fittings,  Heater  and boil'r    39 

Flames,  Color  of 20 

Length  of 22 

Foaming ' 50 

Forced  draught 22 

Friction  clutch 326 

Friction  in  water  pipe 238 

Fuse,  Safety,  Boiler 42,  68 

Electric.. 303,  308 

Gaskets 51 

Gas  meter  reading 243 

Gauge,  Comp'd  ammonia.    90 

Duplex 90 

Steam ,     .    89 


INDEX 


Gauge,  Vacuum .89,  115 

Gear,  Differential 325 

"     Reversing 330 

Gearing,  Lathe 228 

Stacker 332 

Glass  tube,  How  to  cut 247 

Governor,  Automatic,  side 

crank 124 

**         Autorn.,     self- 
contained  129 

"         Pump,  Autom..    85 
Graphite  for  steam-fitting.  246 

Grate,  Air  spaces  in 20 

Gravity  cell 274 

Ground 812 

Hard  Water 195 

Haystacker.... 334 

Heat 174 

"      Latent 18,  175 

"      Utilized 23 

Heater,  Feed  Water 59 

Heating,  Electric 306 

Horse  power 146 

Belting 152 

Boiler 150 

Compound 

engine 150 

Electric..  ..  292 
Evapprat'n..  57 
for  incand. 

lamp    293 

u              Heating  sur- 
face  37,  148 

"  of     traction 

engines  .   .  328 
"  of  waterfall.  147 

k'  of  w  a  t  e  r  - 

wheel 148 

Rating  of. . .  149 
"  Steam    con- 

sumption. 149 
"  Tubular 

boiler 152 

House  Wiring 309 

Hydrogen ,  Liquid 225 

Ice  Making 180 

Incand.  Lamp,  H.  P.  for...  293 

Indicator 154 

card 159 

"        diagram  chart ....  156 

"        examination 162 

"        with  pantograph.  160 

Induction 250 

Injectors,  Classes  of 71 


Injectors,  Parts  of 70 

Size  of. 73 

Working  of 69 

Insulation.  311 

testing 281 

Inverse  ratio 310 

Iron  and  steel 61,  128 

Joints,  Electric  314 

Journal  babbitting 335 

Kilowatt 148,261 

Lamp  sockets 317 

Latent  heat.     . 18,  17o 

Lathe  gearing 228 

"      tools 230 

Law  of  Ohm 291 

Lap  and  lead 102 

Leather  belting  cleaned.      248 

H.  P 152 

Leverage 241 

"        in  safety  valves ..    66 

Lightning,  What  is 251 

Lining  an  engine 120 

Link  motion 144 

Liquid  air 223 

4 '        hydrogen 225 

Lubricators,  How  to  attach    94 

How  to  clean.    95 

"  How  to  run..     93 

"  Triple  sight..     93 

Working  of. . .    94 

Machine  shop 228 

Magnetic  field 250 

Measures  and  weights 236 

Measurements,  Engine —  175 
'  "                Electric.. . .  290 
Chemical.  293 
"                Mechani- 
cal   296 

Mending  band  saw 168 

Meter,  Gas 243 

"      Chemical....  *. 293 

"       Mechanical 296 

Mineral  water 196 

Miner's  inch      238 

Miscellaneous  Q.  and  A.. . .  169 

Molecules 174 

Motions,  Direct  and  Indi- 
rect   117 

of  Crosshead.,169,  172 

Motors,  Stationary 297,  308 

Third  rail 298 

"        Surface  Road 300 


INDEX 


Motor  Brushes  .   .......  273,  298 

Reversing  ...........  308 

M  u.ffler,  Safety  Valve  ......     63 

Multiphase  current  .  ,  .....  252 

Multipliers,  Standard  ......  235 

Nitrogen  ...............     13 

Weight  of.   ......     19 

<Nuts,  Polygonal  ..........  233 

Ohm,  I,aw  of  ..............  291 

Open  coil  ..................  277 

Over  and  under  ...........    98 

Oxygen  ....................     13 

Weight  of  ........     19 

44        in  Combustion  ...     19 

Pantograph  ...........  ...     160 

Parallel  connection  .......  27 


wiring  ............  315 

Pipes,  Standard  Threads  on    39 
Placing  Elect.  Wires  ......     315 

Plant,  Running  Elect  .....  284 

Plunger,  Deep  WTell  ........     87 

Pole,  Positive  ..............  252 

Polygonal  nuts  ............  233 

Potential  ................  :  .  251 

4  '         service,  Constant  278 
Pounding  in  engine  ......  119 

Pressure  in  stand  pipe  ....     14 

Initial  ...........   102 

Safe  boiler  .......  176 

Terminal  ........   102 

Priming  ...................     51 

Pulley  speed  calculation  .  .  239 
Pump,  Ammonia  ..........   197 

Artesian  ...........     84 

Capacity  of  ........     74 

Deep  \vell  .........     87 

Duplex  v'lv.setting    75 
Feed  ...............     73 

governor  ...........     85 

Lift  of  .............     81 

"       testing  .............     79 

Quadrant  ..................  273 

Rack,  Reversing  ..........  331 

Recipe,  mending  band  saw  168 
"     Test'g  iron  and  steel  128 
"      Tracing  paper  ......  274 

"     Solder  and  fluid  ____  205 

"     Steam  cement.  ..... 

Refrigeration  ..............  180 

**  Apparatus.  190,  197 

Methods  of...   185 


Refrigeration,  Principle  of.  181 
Testing       ice 
machinery.  214 

Regulation  of  Feed 57 

Repairs  of  Dynamo 287 

Band  Saw 168 

Resistance  in  Controller  . .  302 

of  metals 310 

Rheostat 272,308 

Rivets 33 

Reversing  rack 331 

an  engine 100 

a  motor 308 

Rubber  gloves,  Use  of   ...  289 
44       belting,  Cleaning.  248 
Reversing  gear,  Single  ec- 
centric   330 

Rules  and  standard  num- 
bers      234 

Running  electric  plant 284 

Ruptures  of  boiler 56 

Rusty  steel,  Cleaning 247 

Safety  fuse,  Boiler 42,  68 

44     Electric... 303,  308 

"     pop  valve 62 

"      valve,  Setting 65 

41      Sizeof 64 

Safe  working  pressure 48 

Series  wound 277,308 

Shafting  accidents 245 

Shaft  lining,  Engine 120 

Short  circuit 312 

Shunt  wound 277 

Slide  valve 96 

"        44     Balanced 133 

44        "     reversing 100 

44        4t     setting 97 

Smoke..   ., 21,53 

44        prevention 25 

Sockets,  Electric 317 

Solder  and  fluid 205 

Specific  gravity 13 

<4     of  ammonia  213 

Square  root 239 

Stacker,  Hay 334 

44        gearing 332 

Standard  babbitts 335 

multipliers 235 

numbers 234 

44        threads  on  pipes    39 

Stationary  motor 297,  308 

Stays,  bolts,  calculation. ..37,  38 

Steam 16 

44      Cleaning  by 247 

44     expansion    18 


INDEX 


Steam  fitting 246 

"     gauge  89 

"         "      test 65 

"     heating 52 

'•      High,  low 17 

• '  pipes,  Cement  for. . .  222 
"  pressure  and  temp.  17 

"     Superheated 17 

"      velocity 18 

Steel  and  iron 61,  128 

Striking  points        122 

Substance,  Three  forms  of.    1 1 

Surface  car,  Elect 300 

Synchronizing 278 

Table,  Ammonia  per  cent..  213 
"        boil,  p'nts  210 

1 '      Areas  of  circles 235 

"      Boiler  H.  P 153 

"      Brine  solutions 195 

"      Cold  storage 206 

"      Co  nducti  vity  of 

metals 310 

"      Engine  H.P 149 

"      Flame  temperature.    20 

"      Grate  space 20 

"  Heat 'g  surface  H.P.  148 
"  Indicator  springs...  154 

"      Polygonal  nuts 233 

"      Rivet  sizes 35 

Steam  pressure 17 

"          "        velocity .     18 

"  Standard  babbitts  . .  335 
' l  Standard  threads ...  39 
"  Traction  engineH.  P.  328 

Tensile  strength 60 

Testing  ammonia 21 1 

' '       boilers 56 

circuit 284 

ice  machinery 214 

insulation 281 

iron  and  steel 128 

pump 79 

steam  gauge 65 

water 15,  195 

Thermal  unit 23 

Thermometers 175,  244 

Third  rail  system 300 

Threads  of  pipe,  Standard.     39 
Tracing  paper,  Recipe  for,  274 


Traction  engine 324 

"       H.P 328 

Transformer 272,293 

Travel   of   crankpin    and 

crosshead 169 

Turning  a  ball 229 

Twist  drill  grinding 231 

Unit,  Electrical 266 

"      Thermal. 23 

Vacuum,  Ammonia  pump.  216 
"         Water  pump..  81,  115 

Valve,  Bevel  of 66 

ki        Bye  pass 207 

"       Check 81 

"       Corliss 135 

•*       Duplex,  To  set 75 

Gate 82 

"        Link  motion 144 

"        rod,  Length  of. ....     97 
"        rod  adjusting,  Cor- 
liss  139 

"        Safety 62 

Slide 96 

*'        Slide,  Balanced....  133 

Ventilator 242 

Vibration,  Anvil 246 

Volt 292 

Water 11 

"        Boiling  points  of...     16 

"       column 42 

"        Composition  of. 12 

"       expansion 12 

"        Freezing 180 

lk        Purifying 12 

' '        measurements 15 

u        as  a  solvent . .     12 

"        tests 15,  195 

Watt 290 

Weights  and  measures ....  236 

Wire,  Placing 315 

"      Size  of? .'.     313 

Wiring,  Electric 309 

Yoke  and  Quadrant.  ..;...  273 

r 
Zero,  Absolute 174 


ICE   MANUFACTURING  PLANT. 


CORLISS  CROSS  COMPOUND  ENGINE. 


Stevens'  Mechanical  Catechism 


WATER 

Life,  as  it  exists  on  our  earth,  depends  on  water 
and  heat.  Water  is  the  most  important  sub- 
stance in  nature. 

QUESTION. — How  does  life  depend  on  water? 

ANSWER. — Water  is  present  everywhere,  in  the 
air,  in  the  ground,  in  wood  and  even  the  hardest 
stone.  About  seven-eighths  of  the  human  body 
is  water.  Without  water  everything  would  be  dry 
and  lifeless. 

Q. — What  are  the  most  important  qualities  of 
water? 

A. — First,  its  abundance  and  universal  presence ; 
second,  its  quality  of  assuming  easily  either  of  the 
three  forms  of  substance,  solid,  liquid  and 
gaseous.  Many  substances  can  be  in  these  three 
forms,  but  water  changes  from  either  one  of  them 
to  the  others  within  a  very  narrow  range  of  tem- 
perature. It  freezes  solid  (ice),  at  32°  F.  (=0°  C.) 
and  turns  to  gas  (vapor)  at  any  temperature,  most 
rapidly  at  the  boiling  point  (212°  F.  or  100°  C.) 


12  QSTfiST.ttDWS    AND    ANSWERS 

Q. — Is  water  an  element  or  a  compound? 

A.— A  compound,  composed  of  two  gases, 
hydrogen  and  oxygen,  in  the  proportion  of  one 
volume  of  oxygen  to  two  volumes  of  hydrogen,  or 
in  weight  one  part  of  hydrogen  to  eight  parts  of 
oxygen. 

Q. — Can  water  be  condensed  by  pressure? 

A. — Very  slightly.  Under  a  pressure  of  one 
atmosphere  it  may  be  compressed  only  about  one 
twenty-thousandth  of  its  bulk. 

Q. — Has  water  any  solvent  power? 

A. — Yes,  it  is  the  most  universal  and  powerful 
solvent  of  all  liquids.  For  this  reason  it  is  rarely 
found  entirely  pure, 

Q. — How  can  water  be  entirely  purified? 

A. — By  changing  it  to  steam  and  condensing 
this. 

Q. — What  taste  or  color  has  pure  water? 

A. — Pure  water  is  tasteless,  odorless,  colorless 
and  transparent. 

Q. — Does  water  expand  or  contract  when 
freezing? 

A. — It  expands  about  1-12  of  its  bulk. 

Q. — When  has  water  the  smallest  bulk? 

A.— At  the  temperature  of  39.1°  F.  (=4°  C.) 

Q. — Would  you  call  the  expansion  of  water  in 
freezing  a  force? 

A. — Yes.  It  exerts  the  tremendous  power  o/ 
30,000  Ibs.  per  sq.  inch. 


WATER  13 

Q.— What  is  specific  gravity? 

A. — Density  as  compared  with  water.  92  Ibs. 
of  ice  equal  100  Ibs.  of  water  at  60°  F.  in  volume. 

Q. — State  the  average  impurities  of  saline  matter 
in  the  Atlantic  Ocean  and  in  the  Dead  Sea? 

A. — The  saline  matter  in  the  Atlantic  Ocean 
amounts  to  2,139  grains  per  gallon,  and  in  the 
Dead  Sea  it  reaches  19,736  grains  per  gallon. 

Q. — What  is  the  proportion  in  area  of  land  and 
water  on  the  globe? 

A. — About  52  millions  sq.  miles  are  land,  and 
about  196  millions  sq.  miles  are  water.  • 

Q. — Where  do  the  clouds  come  from? 

A. — They  are  formed  by  the  constant  evapora- 
tion from  the  immense  water  surfaces  of  the  globe. 

Q. — Is  air  an  element  or  a  compound? 

A. — Like  water,  it  is  a  compound,  composed  of 

• 
20.96  per  cent  oxygen,  79.00  nitrogen  and  0.04  per 

cent  carbonic  acid. 

Q. — Which  of  these  gases  is  the  life-sustaining 
element? 

A. — It  is  the  oxygen.  This  is  the  substance 
whose  chemical  union  with  combustibles  we  'call 
combustion,  whether  in  our  lungs  or  in  a  fire-box. 

Q. — What  is  the  difference  in  weight  between 
air  and  water? 

A. — Air  is  813.67  times  lighter  than  water. 

Q. — Can  it  be  proved  that  air  has  weight? 

A. — Yes,  by  comparing  the  weight  of  a  large 


14  QUESTIONS    AND    ANSWERS 

hollow  globe  when  filled  with  air,  with  its  weight 
after  the  air  has  been  exhausted  by  an  air  pump. 

Q. — How  much  weight  has  the  atmosphere  per 
sq.  inch? 

A. — The  mean  pressure  of  the  atmosphere  is 
stated  at  14. 7  Ibs.  per  sq.  inch. 

Q. — How  is  it  that  this  weight  does  not  crush  us? 

A. — The  pressure  is  exerted  in  all  directions, 
and  permeates  the  whole  body. 

Q.— What  is  the  meaning  of  such  terms,  as  two 
or  three  "atmospheres"? 

A. — An  atmosphere  in  this  sense  is  the  stand- 
ard or  unit  of  air  pressure,  equal  to  the  average 
atmospheric  pressure  at  sea  level  (=14.7  Ibs.  per 
sq.  inch). 

Q. — Is  the  atmospheric  pressure  not  always  the 
same? 

A. — No.*    The  barometer  shows  the  variations. 

Q. — What  is  the  principle  of  the  barometer? 

A. — The  mercury  in  the  closed  vacuum  tube  is 
raised  about.  29. 9  inches  by  the  atmospheric  pres- 
sure entering  through  the  open  tube. 

Q. — How  high  will  the  atmospheric  pressure 
raise  water  in  a  vacuum  tube? 

A. — About  33.9  feet. 

Q.  —What  is  the  pressure  in  pounds  per  sq.  inch 
in  a  column  of  water  in  a  standpipe? 

A. — Multiply  the  height  of  the  column  in  feet 
by  .434.  Engineers  generally  figure  one-half  of 


WATER  15 

one  pound  pressure  per  sq.    inch   for  each  foot 
elevation. 

'  Q- — What  are  the  common  measures  of  weight 
and  contents  for  fresh  water? 

A. — A  gallon  weighs  8  1-3  pounds  an£  contains 
231  cubic  in.  A  cubic  foot  weighs  62  1-2  pounds 
and  contains  1,728  cubic  in.,  or  7  1-2  gallons. 

Q. — What  kind  of  water  would  you  prefer  to  use 
in  a  boiler? 

A. — Rain  or  atmospheric  water. 

Q. — Why  do  you  prefer  rain  water? 

A.  — Because  it  does  not  contain  minerals  which 
scale  the  boiler  heavily. 

Q. — Is  rain  water  considered  pure? 

A.  — Yes,  but  in  their  fall  raindrops  collect  many 
solid  particles  of  dust,  both  in  the  air  and  on  the 
ground.  On  the  other  hand,  spring  water  contains 
almost  invariably  mineral  matter,  which  causes 
corrosion  and  slight  deposit  in  the  boiler.  Rain 
water  is  almost  entirely  free  from  elements  that 
cause  incrustation. 

Q. — What  tests  are  there  for  impure  water? 

A. — Litmus  paper  dipped  in  vinegar  does  not 
return  to  its  true  color  in  water  containing  earthy 
matter  or  alkali.  A  solution  of  a  little  prussiate  of 
potash  will  turn  water  containing  iron  blue.  A 
few  drops  of  a  solution  of  a  little  good  soap  in 
alcohol,  if  put  in  a  vessel  of  water,  will  turn  it  quite 
milky  if  it  is  hard ;  soft  water  will  remain  clear. 


STEAM 

Many  engineers  have  asked  for  an  explanation 
of  the  term  "Steam,"  which  we  have  endeavored 
to  give  in  the  following  questions  and  answers: 

Q. —What  is  "Steam"? 

A.-r-Steam  is  the  gas  from  water  produced  by 
ebullition,  which  is  generally  known  to  take  place 
at  213°  F.  The  passage  of  any  liquid  into  the 
gaseous  state  is  called  vaporization,  and  the  term 
"evaporation"  especially  refers  to  the  slow  produc- 
tion of  vapor  at  the  free  surface  of  a  liquid.  In 
boiling  vaporization  goes  on  not  only  on  the  sur- 
face, but  in  the  liquid  itself. 

Q. — Is  the  boiling  point  of  water  under  all  cir- 
cumstances at  212.8°  F.? 

A. — No.  On  high  mountains,  where  the  atmos- 
pheric pressure  is  very  low,  water  boils  at  a  much 
lower  temperature,  so  that  cooking  cannot  be  done 
except  in  air-tight  vessels ;  and  under  high  pres- 
sure, as  in  steam  boilers,  water  begins  to  boil 
at  a  much  higher  temperature. 

Q. — State  if  the  temperature  of  the  boiling  point 

of  water  increases  the  same  as  the  steam  pressure? 

x  A. — No.     The  following  table  will  explain   the 

different  temperatures  at  different  pressures : 
16 


STEAM  17 

STEAM  PRESSURES  AND  TEMPERATURES 

.Pressure.     Temp.  Pressure.     Temp. 

10 192.4  75 311.0 

15 212.8  80 315.8 

20 228.5  85 3^0.1 

25 241.0  90 324.3 

30 251.6  95 328.2 

35 260.9  I0° 332.0 

40 269.1  120 345.8 

45 276.4  130 352.1 

50 283.2  140 357.9 

55 289.3  150 363.4 

60 295.6  160 368.7 

65 301.3  170 373-6 

70 306.4  180 378.4 

Q. — What  is  the  difference  between  high  and 
low  pressure  steam? 

A. — High  pressure  is  steam  over  15  Ibs. ;  low 
pressure  is  15  Ibs.  or  less. 

Q.— What  is  superheated  steam? 

A. — Steam  removed  from  the  water  boiler  and 
brought  to  higher  temperature  in  a  separate  vessel. 

Q. — Does  water  evaporate  when  the  air  above 
its  surface  is  exhausted  by  an  air-pump? 

A. — The  temperature  could  be  elevated  to  275° 
before  vaporization  takes  place,  and  when  it  does, 
the  action  will  not  be  like  ordinary  ebullition  under 
pressure  of  the  atmosphere,  but  will  be  instan- 
taneous (explosive). 

Q. — What  is  the  boiling  point  of  a  liquid? 


i8 


QUESTIONS    AND    ANSWERS 


A. — A  liquid  boils  when  the  tension  of  its  vapor 
and  the  pressure  it  supports  are  equal. 

Q.— What  is  meant  by  "latent  heat"  in  connec- 
tion with  steam? 

A. — The  effects  of  heat  upon  a  body  are,  i, 
increase  of  temperature ;  2,  expansion,  or  increase 
of  volume;  3,  change  of  state,  as  of  a  solid  to  a 
liquid,  or  of  a  liquid  to  a  gas.  To  transform  water 
at  100°  C.  into  steam,  a  large  amount  of  heat  is 
required,  which  disappears  as  sensible  heat,  and  is 
said  to  become  latent. 

Q. — Which  has  the  more  expansive  force,  water 
or  alcohol? 

A.  — Alcohol  has  more  than  double  the  expansive 
force  of  water  of  the  same  temperature.  The 
steam  of  alcohol  at  174°  is  equal  to  that  of  water 
at  212°.  When  proper  means  can  be  invented  for 
saving  the  fluid  from  being  lost  it  is  supposed  that 
alcohol  can  be  employed  with  great  advantage  as 
the  moving  power  of  engines. 


This  table  shows  the  velocity  (per  second)  at 
which  steam  escapes  into  the  atmosphere  at 
given  Ibs.  of  pressure  above  one  atmosphere. 


PRESSURE  IN 
LBS. 

VELOCITY  IN 
FEET. 

PRESSURE  IN 
LBS. 

VELOCITY  IN 
FEET. 

I 

540 

50 

1736 

3 

8l4 

60 

1777 

5 

98l 

70 

1810 

10 

1232 

80 

1835 

30 

1601 

IOO 

1875 

40 

1681 

120 

1900 

COMBUSTION  AND  FIRING 

x 

Q. — What  is  meant  by  combustion? 

A. — It  is  a  chemical  combination  of  oxygen  with 
combustible  material  of  any  kind,  commonly 
called  fire. 

Q. — State  the  comparative  weight  of  oxygen  to 
nitrogen? 

A. — It  is  1 6  to  14.  x 

Q. — How  much  air  is  necessary  to  consume  a 
given  quantity  of  fuel? 

A. — There  is  a  fixed  proportion  between  the 
oxygen  required  and  the  fuel  gas  to  be  consumed. 

Q. — How  can  this  be  determined? 

A. — We  know  that  oxygen  is  1-5  the  bulk  of  air. 
Five  volumes  of  air  are  necessary  to  produce  one 
of  oxygen;  therefore,  as  two  volumes  of  oxygen 
for  each  of  gas  are  necessary,  it  follows  we  must 
provide  ten  volumes  of  air. 

Q. — What  is  perfect  combustion? 

A. — Combustion  is  perfect,  when  no  gas  is 
developed  that  does  not  instantly  unite  with 
oxygen. 

Q. — What  amount  of  air  is  required  to  consume 
i  Ib.  of  coal? 

A. — It  requires  15  Ibs.  of  air,  on  an  average. 
19 


20  QUESTIONS    AND    ANSWERS 

Q. — How  many  cubic  feet  in  i  Ib.  of  air? 

A. — One  Ib.  of  air  contains  13  9-107  cubic  feel 

Q. — Give  the  proper  air  spaces  for  different 
fuels? 

A. — The  different  sizes  of  air  spaces  between 
grate  bars  for  different  fuels  are  as  follows : 

Schuylkill  anthracite  pea  coal 3€  inch 

Lehigh  anthracite  pea  coal y%  " 

"                        chestnut y%  " 

stove %  " 

broken ^  " 

Cumberland  bituminous X 

Wood ^  to  i  " 

Sawdust 3-16  to  ^  " 

Q. — Of    what    color    are    flames    in    different 
temperatures? 
A. — They  are  as  follows: 

Color.  Temp.  Color.  Temp. 

Red,  j  ust  visible . .  977  deg.  Orange,  deep 201 0  deg. 

"    dull 1290    "  "         clear  ....2190    " 

"    cherry,  dull..  1470    "  White  heat 2370    " 

full.. 1560    "  "     bright 2550    " 

"         "      clear.1830    "  "     dazzling.  ..8730    '• 

Q. — State  the  successive  stages  of  firing  coal, 
and  the  temperatures,  beginning  with  the  match? 

A. — A  slight  friction  of  150°  ignites  the  phos- 
phorous ;  when  this  reaches  500°  the  sulphur  burns ; 
next  800°  ignites  the  wood  or  shavings,  then  1,000° 
ignites  the  coal  gas. 

Q. — How  is  the  philosophy  of  combustion 
known? 

A. — It  is  known  through  chemistry. 


COMBUSTION    AND    FIRING  21 

Q. — What  do  you  understand  by  coal? 

A. — Coal  is  a  compound  substance  and  may  be 
decomposed  by  heat  in  several  distinct  elements. 

Q. — Which  elements  are  of  principal  importance 
in  the  combustion  of  coal? 

A. — Two:  carbon  in  form  of  coke,  and  hydro- 
gen, a  gas. 

Q. — Are  these  all  the  heating  properties  in  coal? 

A. — No,  but  the  principal  ones. 

Q. — Why  does  not  coal  commence  to  burn 
immediately  when  thrown  upon  the  fire? 

A. — Because  coal  must  first  be  heated  and  go 
through  the  process  of  decomposition. 

Q. — How  does  coal  decompose  in  firing? 

A. — loo  Ibs.  of  coal,  when  put  in  a  fire,  develops 
gases  containing  about  24  Ibs.  of  hydro-carbon  and 
free  hydrogen,  9  Ibs.  of  steam  (water),  1.25  Ibs. 
of  sulphur  and  1.2  Ib.  of  nitrogen.  While  these 
are  evaporated  and  consumed,  the  residuum, 
about  60  Ibs.  of  fired  carbon  or  coke,  begins  to 
burn,  leaving  finally  about  4.55  Ibs.  of  ashes 
(incombustible  matter). 

Q. — What  condition  does  smoke  indicate?     * 

A. — It  indicates  poor  combustion. 

Q. — Is  it  understood,  then,  that  when  there  is 
no  smoke  there  is  perfect  combustion? 

A. — No.  The  perfect  combustion  of  coal  in  a 
furnace  can  only  be  effected  by  a  large  enough 
supply  of  oxygen. 


92  QVB0T1ONS    AND    ANSWERS 

Q. — What  is  the  object  of  a  forced  draught? 

A. — To  increase  the  supply  of  oxygen. 

Q. — Does  coke  smoke  while  burning? 

A. — No.  Smoke  only  comes  from  the  gas  dis- 
tilled from  the  coal.  After  the  gas  is  distilled,  that 
which  is  left  is  the  coke. 

Q. — Where  is  the  greatest  heat  when  gas  is 
being  expelled  from  coal? 

A. — In  the  gas. 

Q. — Will  the  coke  or  solid  coal  burn  while 
expelling  gas? 

A. — No.  A  lump  of  coal  may,  however,  be 
expelling  gas  in  one  place  and  burn  in  another 
where  the  gas  has  already  been  expelled. 

Q. — What  is  required  to  burn  anything? 

A. — In  order  to  burn  anything  it  must  be  heated 
to  a  certain  degree  and  kept  up  to  that  heat. 

Q. — How  far  does  a  flame  enter  a  boiler  tube 
of  ordinary  size? 

A. — The  flame  never  enters  more  than  a  few 
inches. 

Q. — Then  state  what  burns  at  the  other  end  of 
the  tube? 

A. — It  is  carbonic  oxide.  It  has  a  low  igniting 
temperature  and  takes  fire  after  mixing  with  the 
atmosphere,  making  a  blue  flame  attending  the 
conversion  of  carbonic  oxide  into  carbonic  acid. 

Q. — The  blue  flame  just  spoken  of — is  it  the 
same  that  entered  the  tube? 


COMBUSTION    AND    FIRING  23 

A. — No.  The  flame  that  entered  the  tube  was 
extinguished,  and  any  combustible  matter  still 
present  went  to  waste. 

Q. — i.  What  is  a  thermal  unit?  2.  How  many 
does  a  pound  of  good  coal  yield? 

A. — i.  It  is  the  heat  required  to  raise  the  tem- 
perature of  i  Ib.  of  water  i°  F.  2.  13,000. 

Q. — What  becomes  of  the  heat? 

A. — Fifty  per  cent  is  utilized,  40  per  cent 
escapes  up  the  chimney,  and  10  per  cent  is  lost  by 
radiation. 

Q. — State  the  weight  of  i  cubic  foot  of  air? 

A. — A  cubic  foot  of  air  weighs  535  grains. 

Q. — State  the  amount  of  air  required  for  the 
combustion  of  i  Ib.  of  good  free  burning  soft 
coal? 

A.  — About  200  cubic  feet. 

Q. — Is  combustion  always  accompanied  by 
flames? 

A. — No.  Combustion  is,  chemically,  a  rapid 
oxidation,  caused  by  the  chemical  union  of  oxygen 
with  the  combustible.  The  rotting  of  vegetable 
matter,  the  rusting  of  iron,  the  oxidation  of  brass 
are  examples  of  combustion  without  flame.  They 
cannot  take  place  without  air,  which  furnishes  the 
oxygen.  Combustion  takes  place  in  our  lungs, 
which  absorb  the  oxygen.  *Pure,  fresh  air  con- 
tains oxygen  in  abundance. 

Q. — Where  do  we  get  the  heat  from? 


24  QUESTIONS    AND    ANSWERS 

A. — The  heat  is  produced  by  the  chemical  union 
of  the  air  with  the  carbon  and  hydro-carbon  of 
the  fuel.  We  might  as  well  expect  to  make  steam 
without  putting  fuel  on  the  grates  as  without  sup- 
plying the  fuel  with  the  proper  amount  of  oxygen 
as  contained  in  air. 

Q. — About  how  much  air  enters  a  furnace 
having  a  good  natural  draught? 

A. — About  530  cubic  feet  per  minute  to  each 
square  foot  of  grate  surface. 

Q. — Suppose  you  had  a  60  H.  P.  boiler  with  25 
sq.  feet  of  grate  surface,  allowing  about  25  per 
cent  of  the  grate  surface  for  air  space,  how  many 
square  feet  for  air  would  there  be,  and  how  much 
would  pass  through  the  grates;  also  how  many 
pounds  of  coal  would  be  consumed  per  hour? 

A. — The  air  space  would  be  6^  sq.  feet,  the 
amount  of  air  passed  through  would  be  about 
198,720  feet  and  the  amount  of  coal  about  1,000  Ibs. 
per  hour.  In  seven  cases  out  of  ten  it  will  be 
found  that  the  grates  are  choked  with  clinkers  and 
the  ash-pit  filled  with  ashes,  so  that  not  more  than 

25  per  cent  of  stated  amount  of  air  could  possibly 
reach  the  fuel.     The  fireman  shovels  in  coal  and 
wonders  why  he  can't  raise  the  steam  pressure, 
never  dreaming  that  the  required  amount  of  air 
for  the  combustion  of  the  amount  of  fuel  thrown 
in  could  not  possibly  pass  through  the  dampers, 
much  less  through  the  clogged  grates. 


COMBUSTION    AND    FIRING 


Q.  —Should  the  grate  slope,  and,  if  so,  in  which 
direction  and  how  much? 

A. — It  should  slope  %  inch  per  foot,  from  the 
front  of  the  furnace  to  the  bridge  wall,  down- 
ward. 

Q. — What  fireman  will  best  prevent  the  .offen- 
sive and  wasteful  formation  of  smoke? 

A. — A  fireman  who  keeps  the  grates  free  for  the 
passage  of  air  and  always  breaks  up  the  coal  into 
lumps  about  the  size  of  a  man's  fist  and  keeps  it 
evenly  distributed  over  the  grates. 

Q. — Do  you  know  of  any  practical 
and  cheap  device  for  the  prevention 
of  smoke? 

A. — A  pipe  inserted  in  the  top  of 
the  stack,  leaving  an  annular  space 
of  three  inches  between  itself  and  the 
inside  of  the  stack,  and  extending 
about  eight  feet  down  into  the  stack 
and  projecting  seven  feet  above  it, 
is  said  to  be  an  excellent  and  cheap 
device  for  preventing  smoke  and  to 
save  ten  per  cent  of  fuel  besides. 

Q. — How  does  it  work? 

A. — At  starting  the  fire,  thick  smoke  issues  from 
the  inserted  pipe,  while  faint  rays  of  smoke  issue 
from  the  annular  space.  These  almost  immedi- 
ately disappear  and  from  the  central  pipe  only 
traces  of  smoke  can  be  seen  to  issue*  This  proves 


«6  QUESTIONS    AND    ANSWERS 

that  a  cold  circular  draught  descends  around  the 
hot  upward  draught,  and  reaching  the  combustion 
chamber  hot  and  in  abundance,  improves  the 
combustion. 

Q. — When  should  fresh  coal  be  thrown  in  on  the 
fire? 

A. — When  the  whole  fire  has  reached  a  white 
heat,  the  door  may  be  opened  and  a  few  shovelfuls 
of  coal  thrown  on  the  front  of  the  grates  and  the 
door  closed  as  quickly  as  possible. 

Q.— What  does  this  do? 

A. — The  gases  distilled  from  the  fresh  coal  will 
be  ignited  while  passing  over  the  hot  coals  on  the 
rear  of  the  grates,  and  instead  of  giving  off  a  dense 
black  smoke  the  hydro-carbons  will  be  entirely 
consumed. 

.  Q.— What  should  be  done  then? 

A. — When  the  coal  has  ignited  it  may  be  pushed 
back  over  the  grates  and  a  fresh  supply  thrown  in 
front  again.  This  kind  of  firing  will  prevent 
smoke,  if  anything  will,  but  it  is  hard  work  for  the 
fireman,  and  when  such  services  are  given  they 
will  be  appreciated  and  encouraged  by  the 
employer. 

Q.— Aboutjiow  thick  should  fires  be  for  different 
coals? 

A. — For  anthracite  coal  the  thickness  should  be 
about  8  inches,  for  soft  coal  about  10  inches  and 
for  coke  about  12  inches. 


COMBUSTION    AND    FIRING  27 

Q. — Suppose  you  could  not  carry  a  fire  bed  of 
the  desired  thickness  without  blowing  off  steam, 
what  would  you  do? 

A. — I  should  reduce  the  grate  surface  area  by 
laying  in  fire  brick  next  to  the  bridge~wall  and 
next  to  the  sides  of  the  furnace  to  the  height  of 
8  or  10  inches. 

Q.— In  starting  a  fresh  fire  under  a  cold  boiler 
how  would  you  proceed? 

A. — First,  have  two  gauges  of  water  in  the 
boiler,  then  cover  the  grate  bars  all  over  with  coal, 
leaving  a  space  in  front  for  some  light  wood  and 
shavings ;  cover  the  back  with  some  heavy  wood 
on  the  coal,  close  the  ash-pit  doors  tightly  and 
partly  close  the  furnace  doors  when  the  wood  is  lit. 
The  coal  on  the  grate  prevents  warping. 

Q. — Why  not  place  the  coal  on  top  at  the 
beginning? 

A. — Because  it  would  prevent  the  free  access  of 
air  to  the  wood.  The  air  enters  through  the  fur- 
nace doors  and  the  draught  carries  the  flames 
between  and  over  the  coal  in  the  rear,  gradually 
heating  it  and  distilling  the  gases  out  of  it,  which 
ignite,  adding  to  the  heat. 

Q. — Then  what  should  be  done? 

A. — After  wood  is  burning,  coal  should  be 
thrown  on,  the  furnace  doors  closed  and  pit  doors 
opened. 

Q. — Is  it  a  good  idea  to  hurry  a  fire? 


28  QUESTIONS   AND    ANSWERS 

A. — No.  It  should  be  allowed  to  burn  gradually 
by  feeding  the  fire  with  a  little  coal  at  a  time. 

Q. — Is  it  good  policy  to  stir  a  fire  often? 

A. — No.  It  should  be  left  alone  as  much  as 
possible. 

Q.— Why  is  it  not  good  policy  to  stir  a  fire  often? 

A.  — Because  it  would  have  a  tendency  to  drop 
all  the  small  coal  and  fire  through  the  grate. 

Q. — How  is  the  draught  controlled? 

A.- — By  the  chimney  damper  and  ash-pit  doors. 

Q. — How  often  should  a  fire  be  cleaned,  and 
when? 

A.— As  of  ten  as  necessary — when  clinkers  pre- 
vent the  admission  of  air  through  the  grates. 

Q. — Can  it  be  seen  by  the  color  of  a  fire  when 
it  should  be  cleaned  or  is  badly  managed? 

A. — Yes.  Dark  spots,  heavy  smoke  and  blue 
flames  are  the  best  points  to  show  it. 

Q.  — How  would  you  clean  a  fire? 

A. — Open  one  of  the  furnace  doors,  shove  the 
live  coals  either  back  or  to  one  side ;  then  rake  out 
the  dead  clinkers,  throw  in  a  little  wood  or  coal  and 
pull  the  live  coals  over ;  then  throw  on  fresh  coal. 

Q. — Would  you  use  wet  coal? 

A. — Some  engineers  do  not  believe  wet  coal 
harmful,  but  others  do. 

Q. — How  and  when  would  you  bank  a  fire? 

A. — First,  clean  the  fire  on  one  side  of  the  fur- 
nace, throw  on  a  few  shovels  of  fine  coal  and  cover 


COMBUSTION    AND    FIRING  29 

it  with  wet  ashes;  tightly  close  the  ash-pit  and 
furnace  doors,  leaving  the  stack  damper  slightly 
open  to  let  out  the  gas.  A  fire  banked  in  this 
manner  will  keep  all  night. 

Q. — How  many  gauges  of  water  would  you  con- 
sider safe  with  a  banked  fire? 

A. — Three  full  gauges. 

Q. — Is  it  a  good  idea  to  entirely  close  the 
chimney  damper  with  fire  on  the  grates? 

A. — No.  It  is  dangerous,  as  gas  may  collect  in 
the  flues  or  tubes,  and  cause  an  explosion  that 
might  do  very  serious  harm. 

Q.— Does  a  banked  fire  benefit  a  boiler? 

A.— Yes.  It  prevents  any  contraction  owing  to 
the  difference  in  temperature. 


LOCOMOTIVE    FIRING 

Q.— How  would  you  fire  a  locomotive  boiler  on 
the  road,  run  light  on  coal,  avoid  much  smoke  and 
have  the  boiler  steam  well? 

A. — Fire  a  little  at  a  time  and  often,  also  keep 
the  fire  level  as  near  as  possible.  Fire  with  £ven- 
sized  coal  and  look  out  for  clinkers  in  the  box; 
also  close  door  after  each  shovelful. 

Q.— What  understanding  have  you  of  steam 
pressure  as  shown  on  the  gauge? 

A.— It  indicates  the  pressure  on  each  square 
inch  against  the  inside  of  the  boiler. 


30  QUESTIONS    AND    ANSWERS 

Q. — Where  would  you  place  a  safety  plug  in  a 
boiler  having  a  fire-box? 

A. — In  the  center  of  the  crown  sheet. 

Q. — Explain  why  steam  is  exhausted  through 
the  stack? 

A.  — Without  it  the  draught  would  be  too  weak 
for  the  needs  of  a  locomotive.  It  forces  the  air 
out  of  the  front  end  up  the  stack,  creating  a 
draught  which  causes  the  gases  and  products  of 
combustion  in  the  fire-box  to  fill  the  space ;  this  in 
turn  allows  the  pressure  of  the  atmosphere  to  force 
fresh  air  up  through  the  grates,  making  a  steady 
and  strong  flow  of  air  into  the  fire-box. 

Q. — Is  enough  air  supplied  through  the  grates  to 
form  perfect  combustion? 

A. — Not  under  all  circumstances. 

Q. — Are  there  other  ways  of  admitting  air  into 
the  fire-box? 

A. — Yes.  Air  is  admitted  over  the  fire  through 
hollow  stay-bolts,  also  air  holes  in  the  fire-box 
door  and  lining. 

Q. — Do  the  holes  in  the  door  answer  any  other 
purpose? 

A. — Yes.  If  drilled  in  line  with  the  lining  holes, 
the  light  from  the  fire  will  light  up  the  deck  and 
coal  space. 

Q. — Does  the  cold  air  that  is  admitted  over  the 
fire  mix  with  the  gas  and  burn  immediately  upon 
entering  the  fire-box? 


COMBUSTION   AND   FIRING  31 

A. — No.  It  is  heated  first,  then  mixes  with  the 
gas  and  burns. 

Q.— State  the  object  of  the  brick  arch  in  the 
fire-box? 

A. — It  is  there  to  hold  the  gas  expelled  by  the 
coal  so  it  will  mix  with  the  air  admitted.  It 
heats  the  air  and  prevents  the  emission  of  dense 
black  smoke.  It  protects  the  flues  from  the  cold 
air  that  passes  through  the  door  when  firing,  and 
checks  the  exhaust's  effect  upon  the  fire,  so  that 
small  particles  of  coal  that  would  otherwise  go 
through  the  flues  and  be  lost,  are  kept  in  the  fire 
to  be  burned. 

Q. — Is  the  brick  arch  a  coal  saver? 

A. — Yes.  It  saves  coal  by  holding  in  the  gas  so 
it  can  burn,  and  prevents  the  flue  sheets  and  flues 
from  sudden  cooling  when  the  fire-box  door  is 
opened.  An  arch  is  a  disadvantage  if  the  side 
sheets  are  patched  or  leaking,  as  the  arch  makes 
them  worse.  It  keeps  them  hot  after  the  other 
parts  of  the  fire-box  are  cool,  consequently  it 
causes  expansion  where  there  should  be  contraction. 

Q.— What  effect  does  an  open  door  have  on  the 
fire  and  flue  sheet  when  an  engine  is  working? 

A.— It  lets  the  air  in  through  the  door  instead  of 
through  the  fire,  which  cools  the  flue  sheet  and 
lowers  the  pressure.  When  firing  see  that  tha 
door  is  closed  after  each  scoop  of  coal. 

Q.— Why  open  and  close  the  door  so  often? 


32  QUESTIONS   AND    ANSWERS 

A. — It  gives  each  previous  shovelful  a  chance  to 
ignite. 

Q. — Is  the  wetting  of  coal  for  locomotives  any 
advantage  over  dry  coal? 

A. — No,  but  with  large  lumps  the  water  gets  in 
the  cracks  and  splits  the  lumps  as  soon  as  heated, 
and  for  small  coal  it  helps  to  coke  into  a  lump,  so 
that  it  will  stay  in  the  box  and  burn  instead  of 
going  out  with  the  first  exhaust. 

Q. — Of  what  use  is  a  blower? 

A.  — It  is  very  useful.  It  makes  a  forced  draught, 
which  prevents  black  smoke,  and  keeps  the  smoke 
and  fire  in  circulation  when  engine  is  shut  off. 

Q. — How  is  smoke  kept  from  trailing  over  the 
train  when  running  shut  off? 

A. — Sometimes  partly  opening  the  door  will 
remedy  the  trouble,  otherwise  the  blower  must  be 
turned  on  a  little  to  force  the  draft.  Good  judg- 
ment should  be  used. 

Q. — Is  it  wasteful  to  have  an  engine  frequently 
blow  off  at  safety  valve? 

A. — Yes;  but  if  the  pressure  can  be  kept  within 
5  Ibs.  of  the  blowing  off  point  it  will  be  easier  on 
,  the  boiler  and  will  save  water  and  coal. 

Q. — Give  the  proper  size  of  a  locomotive  stack 
— inside  diameter? 

A. — It  should  be  2>£  inches  smaller  in  diameter 
than  the  cylinder  of  the  engine. 


BOILERS 
Locomotive  and  Stationary 

Q.— State  the  different  classes  and  styles  of 
boilers  in  use? 

A. — There  are  three  classes — marine,  stationary 
and  locomotive — and  six  styles — marine,  locomor 
tive,  upright,  flue,  tubular  and  water  tube  boilers. 

Q. — How  are  the  different  classes  fired? 

A. — The  marine,  upright  and  locomotive  (hang- 
ing fire-box)  are  fired  internally,  but  the  stationary 
boilers  are  mostly  fired  externally. 

RIVETS 

Q.— Are  boiler  shells  single  or  double  riveted? 

A. — The  end  seams  are  all  single  riveted.  The 
longitudinal  seams  are  single  riveted  for  low 
pressure  and  double  for  high  pressure. 


Q. — Why  are  longitudinal  seams  double  riveted 
and  circular  or  end  seams  single  riveted? 
A. — Because  the  strain  is  greater  on  the  sides 
33 


34  QUESTIONS    AND    ANSWERS 

than  at  the  ends,  as  the  steam  pressure  has  more 
surface  to  work  on. 


Q. — What  is  the  distance  generally  between 
rivets  of  a  single,  or  double  riveted  boiler  shell? 

A. — Single  rivets  are  generally  2%  inches,  and 
double  rivets  2j^  inches  apart. 

Q. — What  should  the  diameter  of  rivets  be  for 
any  size  sheet  to  make  up  the  maximum  shearing 
strength? 

A. — The  diameter  should  be  equal  to  twice  the 
thickness  of  plate  to  be  riveted. 

Q. — What  is  the  usual  distance  between  the  edge 
of  rivet  hole  and  edge  of  sheet? 

A. — The  full  thickness  of  rivet  used. 


LAP  JOINT  RIVETING 

The  following  table  indicates  the  various  sizes, 
etc. ,  of  rivets  for  plates  of  different  thickness : 


SINGLE  RIVETED  LAP  JOINT.  DOUBLE  RIVETED  LAP  JOINT. 


BOILERS 


THICK- 

DIAM- 

DIAM- 

STRENGTH  IN    % 

NESS 

ETER 

ETER 
OF 

PITCH. 

OF  SOLID. 

PLATE. 

RIVET. 

HOLE. 

SINGLE. 

DOUBLE. 

SINGLE. 

DOUBLE. 

i  in. 

1  in- 

ijin. 

2     in. 

2|  in. 

0.66 

0.77 

ft  " 

H  " 

1  " 

2T9    '•' 

2|     " 

O.64 

O.76 

1*  :: 

II 

?:: 

it  " 

aj     " 

2r'«  " 

2J       " 

2|  ;; 

38    " 

0.62 
0.00 

0.58 

0.75 

0.74 
o.73 

This  table  is  applicable  when  steel  rivets  are 
used  in  steel  plates,  or  iron  rivets  in  iron -plates. 
When  iron  rivets  are  used  in  steel  plates,  both 
rivets  and  rivet  holes  should  be  larger  by  1-16  of 
an  inch. 


^W£v 


SINGLE  RIVETED  BUTT  JOINT. 


DOUBLE  RIVETED  BUTT  JOINT. 


When  plates  thicker  than  ^  inch  are  used,  the 
joint  should  be  a  butt  joint  with  double  fish  plate. 
(See  cuts.) 

BRACES  AND  STAY  BOLTS 

Q. — Where  should  braces  be  put  in  a  fire*box 
boiler? 

A. — On  the  crown  sheet,  in  water  leg,  in  dome 
and  on  all  flat  surfaces. 

Q. — What  kind  of  braces  should  be  used? 

A. — In  the  dome,  crowfoot  or  solid  braces;  on 
flat  surfaces  and  between  water  sheets,  stay-bolts ; 
on  the  crown  sheet,  crown  bars  and  stay-bolts ;  in 


36  QUESTIONS    AND    ANSWERS 

the  boiler    shell    crown    radial    braces;    and    in 
corners  gussets. 


Q. — How  is  the  load  on  a  brace  calculated? 

A. — Multiply  the  supported  area  by  the  steam 
pressure  and  divide  the  product  by  the  number  of 
braces.  The  quotient  gives  the  strain  on  each 
brace.  The  law  allows  not  more  than  6,000  Ibs. 
per  sq.  inch  of  cross  section  of  brace.  A  round 
brace  of  i^  inch  diameter  has  i  sq.  inch  area  in 
cross  section. 

Q. — How  can  it  be  known  whether  a  brace  is 
really  carrying  the  intended  load? 

A. — If  it  does,  it  will  give  an  even,  clear  sound 
when  tapped  with  a  hammer  or  the  like. 

Q. — How  are  braces  put  in  properly? 

A. — Have  the  brace  about  1-16  of  an  inch  short, 
heat  it  red  hot  in  the  center  and  put  in  place.  It 
will  shrink  tight  when  it  cools. 

Q.— Why  is  the  flue  sheet  thicker  than  the  boiler 
shell  sheets? 

A.  — Largely  because  it  is  weakened  by  the  many 


BOILERS  37 

flue  holes  cut  in  it,  and  it  has  to  support  the  weight 
and  sag  of  the  flues. 

Q. — Give  the  number  of  square  feet  of  heating 
surface  allowed  to  a  horse-power  in  different  types 
of  boilers? 

A. — For  vertical  12  sq.  feet,  for  horizontal 
tubular  15  sq.  feet. 

Q. — How  is  a  boiler's  horse-power  determined? 

A. — Add  together  all  the  areas,  in  sq.  feet,  of 
heating  surface  up  to  the  fire  line  (shell,  tubes, 
back  head) ;  subtract  from  this  sum  the  cross 
section  area  of  all  the  tubes  and  the  area  of  the 
front  head  less  the  tubes,  and  divide  the  remainder 
by  15  if  horizontal,  by  12  if  vertical.  See  .pages 
148  and  153. 

Q. — Give  tonnage  strain  on  the  crown  sheet  of  a 
fire-box? 

A. — Multiply  the  length  by  breadth  inches, 
divide  by  12  for  feet,  multiply  answer  by  steam 
gauge  pressure  and  divide  by  2,000. 

STAY-BOLTS 

Q. — Explain  the  use  of  stay-bolts? 

A. — They  are  used  to  strengthen  flat  surfaces  in 
steam  boilers. 

Q. — State  the  surface  of  plate  a  stay-bolt  must 
support? 

A. — The  support  is  represented  by  the  area 
enclosed  between  four  bolts. 


38  QUESTIONS    AND    ANSWERS 

Q.— How  is  the  area  between  the  four  bolts 
found? 

A. — By  multiplying  one  distance  by  the  other. 
The  answer  will  be  each  bolt's  support. 

Q. — What  pressure  do  the  four  bolts  have  to 
withstand? 

A.  —Multiply  the  area  by  highest  boiler  pressure. 
The  product  is  the  strain  on  cross  sectional  area. 

Q. — State  the  strain  on  a  single  stay-bolt? 

A. — It  must  not  be  over  6,000  Ibs.  per  sq.  inch 
cross  sectional  area.  Rule:  Multiply  cross  sec- 
tional area  of  bolt  by  6,000,  divide  by  steam 
pressure  and  extract  square  root  of  quotient.  (See 
under  Miscellaneous,  page  239. ) 

Q. — In  examining  the  inside  of  the  boiler,  what 
are  some  of  the  defects  for  which  you  would  be  on 
the  lookout? 

A. — For  missing  pins  from  the  braces,  slack 
braces,  leaky  socket  bolts,  defective  riveting, 
defective  heads  to  the  rivets  and  for  broken  or 
loose  stays. 


Q. — Name  some  appliances  necessary  about  a 
steam  plant? 

A. — A  boiler  and  fittings,  a  pump  or  injector, 
piping  for  the  feed  water  apparatus,  steam  pipes, 
globe  valves,  feed  valves,  feed  water  heater,  steam 
trap,  chimney  and  dampers,  safety  valve,  check 
valve,  the  fire  front  containing  the  fire  and  pit, 


BOILERS 


39 


also  flue  doors,  grate  bars,  and  bearing  bars,  dead 
plates,  man  and  hand  hole  plates,  thimbles,  water 
gauge  cocks  and  glass  gauge,  blow-out  cock, 
fusible  plugs,  steam  gauge,  fire  tools,  flue  brush, 
gaskets  and  scaling  tools,  also  hose  for  washing 
out  the  boiler,  shovel,  slice  bar,  rake,  hoe,  etc. 

STEAM   FITTINGS 


Return  Bend. 
Ffange  Union."        Close  Pattern. 


Return  Bend. 
Open  Pattern. 


Pipes  of  y£"  bore  have  27  threads  to  the  inch; 
pipes  of  X  or  l/%"  nave  I8»  pipes  °f  1A  or  %"  have 
14;  pipes  of  from  i  to  2"  have  \\l/2  ;  larger  ones,  8. 


CIpseMpple, 


LockflQt, 


Caft*  Plug 

Q.__Name  the  principal  features  of  the  brick- 
work about  a  horizontal  boiler? 


40  QUESTIONS    AND    ANSWERS 

A. — Binder  bars,  back  stays,  cleaning  out  doors, 
iron  rollers  and  plates  for  the  boiler  lugs  to  rest  on. 
Q. — What  is  a  globe,  valve? 

A. — It  is  a  valve  in  a  round 
or  globe  chamber,  used  on 
boilers,  engines,  etc. 

Q. — What  are  thimbles  on 
boilers? 

A. — They  are  heavy  castings 
riveted  on  the  upper  shell  of 
the   boiler  with  planed  flanges 
to  which  are  bolted  the  safety 
Globe  Valve         valve  3nd  main  steam  pipe. 
Q. — is  a  horizontal  boiler  placed  level  on    its 
saddles? 

A. — No,  it  is  given  a  slight  tilt  (i^  inch)  toward 
the  back,  so  all  the  water  can  be  drained  out 
through  the  blow-off.  This  also  insures  having 
always  water  at  the  end  opposite  the  gauge  cock. 
Q. — How  are  the  sizes  found  of  steam,  water 
and  gas  pipes? 

A. — By  measuring  their  inside  diameters. 
Q. — How  do  you  find  the  size  of  a  boiler  tube, 
flue  or  gauge  glass? 
A. — By  the  outside  diameter. 
Q. — In  taking  charge  of  a  new  plant,  what  is 
the  first  thing  to  do? 

A. — Look  after  the  water  and  steam  pipes,  als© 
the  valves  connected  with  them. 


BOILERS  41 

Q.— Does  water  become  lighter  or  heavier  in  a 
boiler  under  steam  pressure? 

A. — It  becomes  lighter  per  cubic  foot  as  its 
temperature  increases. 

Q. — State  as  near  as  practicable  the^lace  to  tap 
an  upright  boiler  for  the  lower  gauge  cock? 

A. — Two  thirds  the  distance  between  the  two 
flue  sheets,  measuring  from  the  bottom  flue  sheet. 

Q.— Where  would  you  place  the  lower  gauge 
cock  in  a  submerged  tube  vertical  boiler? 

A. — From  2^  to  4  inches  above  the  top  flue 
sheet,  according  to  the  size  of  the  boiler,  so  that 
the  top  ends  of  the  tubes  would  always  be 
submerged. 

Q.— Where  is  the  water  line  of  a  horizontal 
tubular  boiler? 

A.— From  one  and  a  half  to  two  inches  above 
the  tubes. 

Q.— Where  is  the  fire  line? 

A. — On  outside  of  shell  and  in  line  with  the 
upper  row  of  tubes. 

Q. — Where  is  the  lower  gauge  cock  in  a  hori- 
zontal tubular  boiler? 

A.— An  inch  and  a  half  to  two  inches  above  the 
upper  row  of  flues. 

Q. — Where  is  the  water  pipe  tapped  in  a  boiler 
head  for  a  water-combination  column?  Where 
is  the  steam  pipe  tapped,  and  what  size  of  pipe  is 
used  for  making  the  two  connections? 


•  QUESTIONS   AND    ANSWERS 


A. — The  water  pipe 
is  generally  tapped 
centrally  between  the 
two  upper  rows  of 
flues  and  the  shell  of 
boiler.  The  steam 
pipe  is  tapped  in  the 
top  of  the  shell  or  in 
the  dome.  The  con- 
necting pipes  should 
not  be  smaller  than 
i  %  inch  diameter. 

Q.  —  How  often 
would  you  blow  out 
the  gauge  glass  during 
the  day? 

A. —About  four 
times,  or  as  often  as 
necessary. 

Q. — Is  a  glass  gauge  always  perfectly  reliable? 
A. — No.     The  gauge  cocks  must  be  tried  even  if 
a  glass  gauge  is  used. 

Q.— Where  is  the  safety  plug  usually  placed  in 
a  water  tube  or  flue  boiler? 

A. — In  water  tube  boilers  they  are  generally 
placed  four  inches  above  the  bottom  of  the  drum, 
and  not  in  the  tubes.  In  flue  boilers  it  is  some- 
times screwed  in  the  top  of  one  of  the  upper  flues, 
but  of  late  it  is  the  custom  to  tap  the  crown  of  the 


TOP  OF  UPPER 
ROW  OF  FLUES 


TO  WATER  SPACE 
OF  BOILER  8ETVKI 
THE  TWO  UPPER 
Of  FLUES  AND  SHELL 


BOILERS  43 

shell  about  15  inches 
back  of  the  dome  and 
there  insert  a  half -inch 
pipe,  reaching  to  within 
2^  of  an  inch  of  the  flue 
line.  The  top  of  this 
pipe  is  tapped  into  a 
brass  chamber,  in  the 
top  of  which  the  safety  fuse  plug  is  screwed  in. 

Q. — How  does  this  arrangement  work? 

A.  — When  the  water  in  the  boiler  falls  below  the 
lower  end  of  the  safety  plug  pipe  (indicated  by  a 
dotted  line  in  the  cut),  the  dry  steam  enters  it, 
passes  into  the  chamber  and  fuses  the  plug,  the 
steam  escapes  and  gives  warning.  See  also  page  68. 

Q. — At  what  temperature  does  the  plug  fuse, 
and  what  is  it  made  of? 

A. — It  is  made  of  Banca  tin  which  fuses  at 
420°  F. 

Q. — What  causes  channeling  and  grooving  in  a 
boiler? 

A.  — They  are  caused  by  the  mechanical  action 
produced  by  unequal  expansions  and  contractions. 

Q. — Where  would  you  feed  water  into  a  boiler 
to  prevent  grooving,  etc.  ? 

A. — Feed  near  the  water  level  of  the  boiler 
instead  of  near  the  bottom. 

Q.— Which  is  the  best  arrangement  of  the  feed 
pipe? 


44  QUESTIONS    AND    ANSWERS 

A.— It  should  enter  the  front  head  just  above 
the  tubes  and  a  few  inches  away  from  the  shell. 
It  should  then  extend  back  to  within  a  foot  or  so 
of  the  back  head,  then  cross  over  and  discharge  on 
the  opposite  side,  downward,  between  the  tubes 
and  shell.  In  this  way  the  feed  water  becomes 
well  heated  before  discharging  into  the  boiler. 

Q. — How  large  should  a  feed  pipe  be? 

A. — According  to  the  size  of  the  boiler,  from  i 
to  i^  inches. 

Q.— How  large  should  the  blow-off  pipe  be? 

A. — Ordinarily  2  to  2)4  inches  diameter. 

Q. — Where  should  the  blow-off  pipe  be  attached 
to  the  boiler? 

A. — Underneath  its  back  end.  The  shell  should 
be  re-enforced  with  a  flange  riveted  on,  and  the 
pipe  should  be  protected  from  the  action  of  the 
flames  and  hot  gases  from  the  furnace  by  a  fire 
brick  stand. 

Q. — Why  is  malleable  iron  used  for  the  elbows 
in  the  fire? 

A.— Cast  iron  ones  would  burn  or  break. 

Q. — Is  it  dangerous  to  empty  a  boiler  when  the 
tubes  or  flues  are  hot? 

A.  — Yes ;  and  it  is  also  dangerous  to  hastily  fire 
up  a  boiler,  because  where  the  draught  and  com- 
bustion are  sufficient  for  a  white  heat,  the  plates, 
no  matter  how  good  they  may  be,  cannot  with 
certainty  resist  the  terrible  heat. 


BOILERS  45 

Q. — State  causes  of  defective  circulation. 

A.— It  is  caused  by  flues  being  too  close  together, 
scale  thickening  on  them,  and  flues  set  zigzag. 

Q. — What  construction  of  a  boiler  would  be  con- 
sidered successful  and  economical? 

A. — For  a  tubular  boiler  place  the  flues  in 
vertical  rows,  leaving  out  the  center  row;  good 
circulation  is  when  water  goes  down  in  the  center 
and  rises  at  the  sides  where  the  heat  strikes  it. 


OOOOO  OOO 
OOOOO  OOO 
OOOOO  OOO 

oooo    oo 


Q. — How  much  steam-space  is  there  in  a  boiler? 

A.— About  %  of  the  internal  capacity.  (In  the 
cut  the  water  surface  is  indicated  by  dotted  lines, 
and  the  height  of  the  steam  space  by  b. ) 

Q.— Give  the  space  between  the  flues  of  a  well- 
made  boiler? 

A. — The  proper  space  should  be  half  the 
diameter  of  the  flue.  (See  the  cut  above.) 

Q. — What  amount  of  water  in  weight  can  be 
evaporated  by  one  pound  of  good  coal? 


46  QUESTIONS    AND    ANSWERS 

A. — The  average  is  from  six  to  ten  pounds. 

Q. — What  waste  of  heat  is  there  if  1-16  inch  of 
scale  is  in  the  boiler? 

XA. — Some  of  the  best  authorities  claim  from  10 
to  15  per  cent  of  fuel,  and  in  this  proportion 
upward  according  to  thickness  of  scale. 

BOILER   EXPLOSIONS 

Q. — What  causes  a  boiler  to  explode? 

A. — It  may  be  one  or  several  of  various  causes. 
Defects  in  material  or  construction,  or  improper 
management  account  for  most  explosions. 

Q. — What  is  the  scientific  explanation  of  an 
explosion? 

A. — A  boiler  explodes  when  the  pressure  within 
exceeds  its  resisting  power. 

Q. — What  decides  a  boiler's  resistance? 

A. — The  strength  of  its  weakest  spot.  It  is 
there  that  an  excessive  pressure  breaks  through 
first. 

Q. — Why  are  the  parts  surrounding  the  weakest 
spot  affected? 

A. — The  break  decreases  their  resisting  power, 
while  the  shock  and  the  sudden  increase  in  the 
generation  of  steam  manifold  the  pressure. 

Q. — Does  all  the  water  instantly  change  to 
steam? 

A. — No,  but  with  a  speed  increasing  at  such  a 
rapid  rate  that  it  seems  instantaneous. 


BOILERS  47 

Q. — Is  low  water  often  a  cause  of  explosion? 

A. — Yes,  when  the  engineer  tries  to  fill  the 
boiler  quickly,  instead  of  very  slowly.  If  a  large 
amount  of  cold  water  suddenly  enters  a  hot  boiler 
with  a  high  pressure,  too  much  of  it^changes  to 
steam,  at  once  raising  the  pressure  beyond  the 
resistance  of  the  boiler. 

Q.— Is  it  proper,  then,  to  feed  water  into  a 
boiler  when  the  water  is  out  of  sight? 

A. —  Under  no  circumstances. 

Q. — What  would  you  do? 

A. — I  should  immediately  draw  the  fire,  if  a 
light  one ;  if  a  heavy  one,  I  should  cover  it  over 
with  wet  ashes  to  deaden  the  heat. 

Q. — Why  not  draw  out  a  heavy  fire? 

A. — Because  it  would  make  more  heat  by 
raking. 

Q. — What  would  you  do  if  the  water  was  too 
high  in  the  boiler? 

A. — Carefully  open  the  blow-off  and  let  out  one 
gauge  of  water. 

Q. — What  injury  and  danger  are  caused  by 
heavy  scale  in  a  boiler? 

A. — The  heat  from  the  boiler  plates  is  not  com- 
municated to  the  water  directly,  but  through  the 
incrustation,  a  bad  conductor.  This  necessitates 
an  overheating  of  the  plates,  which  deteriorates 
and  weakens  them  rapidly. 

Q.  — What  is  a  bagged  or  blistered  boiler? 


48  QUESTIONS    AND    ANSWERS 

A.  — A  bag  is  a  bulging  out  of  the  plate ;  a  blister 
is  a  bulging  out  not  of  the  whole  plate,  but  of 
the  outer  layer  split  from  the  inner.  These 
defects  are  caused  by  too  much  sediment  or  scale. 
They  weaken  the  boiler  very  much. 

Q. — How  are  these  defects  remedied? 

A. — By  cutting  the  bagged  or  blistered  piece 
out,  and  riveting  a  hard  patch  on  the  inside  of  the 
boiler. 

Q. — Why  on  the  inside? 

A. — Because  if  put  on  the  outside,  the  hole 
would  form  a  pocket  for  sediment. 

Q. — How  would  you  find  the  safe  working  pres- 
sure of  a  boiler? 

A. — Multiply  twice  the  thickness  of  shell  by  the 
T.  S.  stamped  on  boiler  plate  and  divide  answer 
by  6  times  diameter  of  shell  in  inches.  If  double 
riveted  multiply  by  .70;  if  single,  by  .56.  (Ans. 
in  Ibs.  of  pressure  gives  the  safe  load,  at  which  the 
safety  valve  is  set.) 

Q. — How  is  the  safe  working  pressure  found  in 
cylindrical  boilers? 

A. — Multiply  one-sixth  of  the  lowest  tensile 
strength  by  the  shell's  thickness  (expressed  in  parts 
of  an  inch)  at  the  thinnest  part,  and  divide  the 
product  by  the  inside  radius  (half  diameter)  in 
inches.  The  answer  will  be  the  pressure  allowable 
per  square  inch  of  surface  for  single  riveted;  if 
double  riveted  add  20  per  cent. 


BOILERS  49 

Q. — Do  these  two  rules  give  the  same 
result? 

A. — No,  but  they  are  both  used  by  different 
engineers,  and  are  both  claimed  to  be  service- 
able. 

Q.— Which  do  you  consider  the  safer,  drilled  or 
punched  holes  in  boilers,  for  rivets,  etc? 

A.— Drilled  holes. 

Q. — Describe  a  good  way  of  keeping  a  boiler 
clean? 

A.  — Every  boiler  should  be  supplied  with  a  sur- 
face blow-off,  as  a  large  percentage  of  the  foreign 
matter  held  in  suspension  in  water  rises  at  the 
boiling  point  and  can  then  be  blown  off  before  it 
has  had  time  to  deposit  on  the  surface  and  flues.  If 
not  blown  off,  the  heavier  particles  will  be  attached 
b  each  other  until  they  become  sufficiently  heavy 
to  fall  to  the  bottom,  when  they  will  be  deposited 
51  the  form  of  scale,  covering  the  whole  internal 
surface  of  the  boiler  below  the  water  line. 

Q. — Where  is  the  surface  blow-off  tapped? 

A. — It  is  tapped  in  the  crown  of  the  boiler 
and  its  pipe  is  bent  so  as  to  lie  even  with  1:he 
average  water  level.  When  the  valve  is  opened, 
the  outrushing  steam  carries  the  surface  water 
and  any  light  matter  floating  on  it  along  into  the 
catch  basin.  This  device  is  usually  called  the 
skimmer. 

Q. — When  is  the  proper  time  and  how  would 


50  QUESTIONS    AND    ANSWERS 

you  blow  out  a  boiler  for  cleaning 
purposes? 

A.  —  Allow    the    furnace    and 
boiler  to  cool  down,  open 
blow-off  so  the  water  and 
mud  will  escape, 
then  wash  out  with 
a  hose.    Scrape  the 
flues     if    possible, 
pull     out    all    the  Straightway  Blow-off  Valve 
sediment   and   scale   left  on   the   bottom   of  the 
shell  with  a  long-handled  hoe  through  the  hand 
hole  of  the  boiler  and  thoroughly  rinse  with  water. 

Q. — Suppose  a  boiler  was  found  badly  corroded 
and  pitted  internally  along  the  water  line,  and 
covered  with  a  heavy  deposit  of  sediment,  baked 
on  hard,  what  should  be  done? 

A. — Get  inside  the  boiler  and  thoroughly  scrape 
the  shsll,  getting  down  to  the  sound  plate,  then 
with  a  stiff  wire  brush  thoroughly  oil  or  paint  the 
corroded  portion  with  red  lead  and  boiled  linseed 
oil,  three  coats. 

Q. — What  are  the  causes  of  * 'foaming"? 

A. — Foaming  comes  from  various  causes,  such  as 
the  mixing  of  water  with  steam,  high  water, 
irregular  firing  or  feeding,  impure  or  greasy  water, 
too  small  steam  space,  dirty  boiler,  changing  of 
water,  etc. 

Q. — How  is  it  known  when  a  boiler  foams? 


BOILERS  '  51 

A. — It  can  be  seen  in  the  gauge  glass  by  the 
water  suddenly  moving  up  and  down,  or  by  the 
sputtering  at  the  gauge  cock. 

Q. — Can  foaming  be  overcome? 

A. — Yes,  by  partly  closing  large  valves,  opening 
fire  doors  and  feeding  water  into  boiler. 

Q. — What  is  meant  by  a  boiler's  "priming"? 

A. — Entrance  of  water  together  with  steam  into 
the  steam  pipe,  caused  by  high  water,  narrow 
steam  pipe  and  sudden  opening  of  valve. 

Q. — How  would  you  remedy  it? 

A. — By  opening  the  valve  slowly,  or  lowering 
water  in  the  boiler. 

Q. — How  would  you  gasket  a  steam  joint  so  the 
gasket  can  always  be  taken  out  and  replaced  with- 
out injuring  it? 

A. — By  rubbing  a  little  graphite  and  oil  between 
the  face  of  the  flanges  and  the  gasket,  both  sides. 

Q. — How  would  you  remove  a  man  or  hand  hole 
plate  from  a  boiler? 

A. — Simply  loosen  nut,  remove  brace  (dog  or 
crab),  and  turn  the  plate  to  narrow  side  and  take 
out. 

Q. — Why  is  a  hand  or  man  hole  plate  made 
oval  instead  of  a  true  circle? 

A. — So  they  can-  be  taken  out  and  put  in  and 
new  gaskets  put  on. 

Q. — When  you  have  a  battery  of  two  boilers  or 
more  and  one  boiler  has  80  Ibs.  steam  pressure  and 


52  QUESTIONS    AND    ANSWERS 

the  rest  are  cold,  how  would  you  proceed  to  con- 
nect them  together? 

A. — Simply  fire  up  the  cold  boiler  and  raise 
steam  pressure  to  equal  the-  one  to  which  you 
wish  to  connect  it.  Never  under  any  circumstances 
turn  high  into  low  pressure  or  hot  into  cold, 
because  the  sudden  expansion  may  cause  a  serious 
rupture  and  may  cost  you  your  life. 

Q. — What  is  the  first  thing  you  would  do  on 
entering  the  boiler  room  in  the  morning? 

A. — See  how  much  water  is  in  the  boiler  by  try- 
ing the  gauge  cocks,  etc. 

Q.— Then  what  would  you  do? 

A. — Start  a  fire  if  I  had  one  or  two  gauges  of 
water. 

STEAM   HEATING 

Q. — How  would  you  open  a  steam  valve  to 
supply  steam  to  a  building  for  heating  in  the 
morning? 

A. — Open  the  valve  slightly  and  wait  until  the 
pipe  stops  pounding,  then  gradually  open  a  little 
more;  it  saves  joints,  gaskets,  pipes,  etc.  When 
opening  valves,  make  sure  that  the  valve  at  the 
end  of  the  return  pipe  is  open  until  hot,  then  close 
it. 

Q. — How  is  the  amount  of  pipe  required  for 
properly  heating  a  room  calculated? 

A.— By  the  following  rules: 


BOILERS  53 

One  cub.  foot  of  boiler  to  every  1,500  cub.  feet  of 
space.  One  H.  P.  of  boiler  to  40,000  cub.  feet  of 
space.  One  superficial  foot  of  steam  pipe  to  six 
superficial  feet  of  glass  in  windows.  One  super- 
ficial foot  of  steam  pipe  to  100  sq.  feet  of  wall,  ceil- 
ing or  roof.  One  sq.  foot  of  steam  pipe  to  80  cub. 
feet  of  space. 

Q. — How  do  you  find  the  heating  surface  of  a 
radiator? 

A. — Multiply  the  total  length  of  all  the  pipes  by 
the  outside  circumference  in  inches,  and  divide  by 
144.  The  answers  give  the  square  feet. 

Q. — Which  is  the  best  way  to  thaw  out  frozen 
steam  pipes? 

A. — By  laying  some  old  cloth  or  waste  on  the 
pipe  and  pouring  on  boiling  water,  the  pipe  can  be 
thawed  out  in  10  minutes. 

SMOKE   AND    CHIMNEY 

Q. — Would  it  be  proper  to  have  the  chimney 
rough  inside? 

A. — No;  it  should  be  as  smooth  as  can  possibly 
be  made,  and  the  area  a  little  larger  towaitl  the 
top  than  at  the  bottom  (inside). 

Q. — How  much  larger  should  the  space  be  where 
the  smoke  or  gases  return  through  the  flues 
than  the  grate  surface? 

A. — It  should  be  one-fifth  larger  in  area  than 
the  grate  surface. 


54 


QUESTIONS   AND   ANSWERS 


Q. — Where  would  you  consider  the  proper  place 
to  close  in  against  the  sides  of  an  externally  fired 
boiler  with  brick  (fire  line)? 

A. — About  in  line  with  the  center  of  upper  row 
of  flues  all  along  the  full  length  outside  of  boiler. 


SIDE  VIEW 

This  cut  shows  the  proper  way  of  enclosing  a 
boiler  in  brickwork.  The  figures  give  the  dis- 
tances in  inches. 

Q. — Where  does  the  greatest  effect  of  the  fire  on 
the  bottom  of  an  externally  fired  horizontal  boiler 
take  place? 

A. — Just  back  of  the  bridge  wall. 

Q. — From  where  is  the  height  of  a  chimney 
measured? 

A-— From  the  top  of  the  grate. 

Q. — What  makes  a  chimney  draw? 


BOILERS 


55 


A.  — The  difference  between  the  weight  of  the 
column  of  heated  gases  within  and  an  equal  column 
of  cooler  air  without. 

Q. — Upon  what  does  the  draught  capacity  of  a 
chimney  depend? 


END   VIEW 

A.— Upon  its  height,  cross  section  area,  and  upon 
the  temperature. 
Q. — State  the  size  of  chimney  necessary  to  fully 

relieve  the  tubes  or  flues  of  a  boiler  or  boilers  of 

» 
smoke,  and  give  height? 

A. — The  chimney  should  be  one-fifth  larger  in 
area  than  all  the  tubes  or  flues  combined,  so  as  to 
afford  an  ample  passage  for  all  the  gases.  The 
top  should  project  at  least  10  feet  above  the  high- 
est building  in  the  immediate  vicinity,  to  avoid  all 
downward  currents  of  the  atmosphere. 


56  QUESTIONS    AND    ANSWERS 

BOILER   TESTING 

Q. — Is  the  hydraulic  test  or  the  hammer  test 
better?  and  why? 

A.  — The  hammer  test  is  always  reliable  because 
a  flawless  metal  gives  a  clear  sound,  and  every 
part,  inside  and  out,  is  examined  by  itself.  In  the 
hydraulic  test  a  boiler  may  get  strained,  and  when 
heated  afterward,  the  expansion  may  bring  out  a 
leak.  Government  and  insurance  inspectors 
employ  the  hammer  test. 

Q. — How  do  you  find  a  broken  or  loose  stay  or 
rivet? 

A. — By  holding  a  hammer  against  one  side  and 
striking  the  other  side  with  another  hammer.  Any 
looseness  can  be  discovered  in  this  way  by  the 
feeling. 

Q. — If  tested  by  the  hydraulic  test  how  much 
pressure  is  sufficient  to  test  the  boiler  so  as  to 
carry  a  certain  amount  of  steam  pressure? 

A. — The  hydraulic  pressure  test  should  be  one- 
half  more  than  the  steam  pressure  to  be  carried, 
viz. :  If  steam  pressure  is  to  be  80  Ibs.  the  hydraulic 
test  should  be  120  Ibs. 


Q. — What  is  it  that  ruptures  a  boiler? 
A. — The  pressure  within  it,  and  strains  caused 
by  unequal  expansion  and  contraction. 
To    avoid     this    trouble     it    is     necessary    to 


BOILERS  57 

exercise  great  care  in  raising  steam.  The  fire 
should  be  increased  gradually  and  the  boiler  have 
at  least  four  inches  of  water  above  the  top  row  of 
flues  so  the  temperature  may  be  gradually  raised. 

Q. — Is  it  injurious  to  a  boiler  to  open  the  fire 
doors  often  and  suddenly  cool  the  fire  and  sheets? 

A. — Yes;  it  is  very  unsafe. 

FEED    REGULATION 

Q. — Suppose  you  had  a  battery  of  three  boilers 
and  the  only  valves  near  the  boilers  on  the  feed 
pipe  were  check  valves,  how  would  you  feed  the 
boilers  evenly  without  using  globe  valves  between 
the  checks  and  boilers? 

A. — First,  fire  the  boilers  evenly;  second,  keep 
the  pumps  running  steady,  and  if  one  boiler  should 
happen  to  receive  more  water  than  the  others  use 
the  blow-off  valve  of  that  particular  boiler  and 
regulate  the  height  by  it. 

Q. — Can  uneven  feeding  be  prevented? 

A. — Yes,  by  partially  closing  the  stop  valves  of 
the  boiler  or  boilers  with  high  water,  and,  if 
necessary,  by  opening  the  stop  valves  of  the  low 
water  boilers  a  little  more. 

BOILER    HORSE-POWER 

Q. — How  can  you  find  the  amount  of  water  evap- 
orated in  a  boiler? 

A. — Take  the  mean  between  the  widths  of  the 


58  QUESTIONS    AND    ANSWERS 

two  levels  at  the  beginning  and  at  the  end  of  a 
space  of  15  minutes,  as  indicated  by  the  glass 
gauge.  (See  cut,  pp.  42,  45.)  Multiply  the  con- 
stant length  of  water  surface  with  this  mean  width 
and  multiply  their  product  by  4.  This  gives 
the  amount  evaporated  in  cubic  inches.  Divid- 
ing the  result  by  1728,  you  get  the  answer  in  cubic 
feet.  This  test  is  not  recommended,  though  used. 

Example:  If  the  glass  gauge  shows  a  difference 
of  one  inch,  we  measure  across  the  face  of  the 
boiler  half  an  inch  above  the  last  level.  If  this 
measures  48  inches  and  the  boiler  is  14  feet  long 
(=168  in.),  we  have  48X168=8064.  Multiplied  by 
4=32,256  cub.  in.  per  hour,  or  18%  cub.  feet. 

Q. — Can  you  know  from  the  amount  of  water 
evaporated  in  one  hour,  how  many  horse-powers 
have  been  developed? 

A.— Yes. 

Q. — How  many  cubic  feet  of  water  evaporated 
in  one  hour  equals  a  horse-power? 

A.  —One-half  cubic  foot,  3^  gallons  or  864  cubic 
inches. 

Q.— Then,  in  our  example,  how  many  horse- 
powers were  indicated? 

A.— Two  times  18^,  =37><  H.  P. 

Q. — How  can  you  find  the  horse-power  of  a 
tubular  boiler  by  the  heating  surface? 

A. — First  find  the  number  of  square  inches  of 
heating  surface  around  boiler  shell  from  fire  line  to 


.       BOILERS       m  59 

fire  line  and  in  the  flues;  divide  by  144  to  get 
square  feet;  divide  quotient  by  15  if  horizontal 
tubular,  and  by  12  if  locomotive  or  vertical  boiler 
to  get  H.  P. 


FEED-WATER  HEATER 

Q. — How  many  types  of  feed- water  heaters  are 
there? 

A. — Two.     The  open  heater  and  the  closed. 

Q. — What  is  the  difference  between  them? 

A. — In  an  open  heater  the  exhaust  steam  comes 
directly  in  contact  with  the  feed -water,  in  a  closed 
heater  it  does  not. 

Q. — What  is  the  object  of  a  feed  -  water 
heater? 

A. — To  save  fuel  by  making  use  of  the  exhaust 
steam  from  the  engine  to  heat  the  feed-water. 

Q. — At  what  temperature  will  a  heater  deliver 
water  to  a  boiler? 

A. — That  depends  upon  the  type  of  heater  and 
other  conditions.  A  good  heater  of  ample  propor- 
tions should  raise  the  temperature  of  the  feed- 
water  up  to  200°  F. ,  or  higher. 

Q. — What  else  is  a  heater  good  for  besides  heat- 
ing the  feed-water? 

A. — It  also  purifies  the  water  by  extracting  the 
scale-producing  matter,  and  also  the  mud. 


60  QUESTIONS    AND    ANSWERS 

Q. — In  using  an  open  heater  is  there  any  danger 
of  flooding  the  cylinder,  and  if  so,  how? 

A. — If  there  should  be  any  stoppage  of  the  out- 
flow of  feed-water,  it  would  flood  the  cylinder 
through  the  engine  exhaust  pipe,  and  perhaps 
cause  a  wreck. 


TENSILE  STRENGTH 

The  tensile  strength  of  metals  is  the  load  that 
would  break  a  bar  of  one  inch  area  in  cross  sec- 
tion if  applied  in  the  direction  of  its  length. 

For  a  test  of  the  tensile  strength  of  iron  or  steel 
boiler  plates,  narrow  strips  are  sheared  from  plates 
selected  at  random  from  a  pile  of  them  rolled  at  the 
same  time — we  will  say  the  plates  are  steel  and  a 
quarter  of  an  inch  in  thickness.  These  strips  are 
at  the  middle  reduced  to  a  quarter  of  an  inch  each 
way  (square). 

Suppose  the  testing  machine  pulls  the  first  of  4 
strips  asunder  at  3,999  Ibs.  register,  the  second 
breaks  at  4,001  Ibs.  and  the  last  two  at  exactly 
4,000  Ibs.  each.  Adding  these  all  together  we 
have  the  sum  of  16,000  Ibs.,  which,  divided  by  4, 
the  number  of  strips  tested,  gives  us  4,000  Ibs.  as 
the  mean  breaking  strain  of  a  quarter  square 
inch  of  sectional  area  of  steel. 

Multiply  this  by  the  number  of  quarter  square 


BOILERS  6 1 

inches  in  i  square  in.  and  we  have  the  tensile 
strength  in  i  square  in.  of  section.  There  being 
1 6  quarter  in.  square  in  i  square  in.  would  give  16 
times  4,ood,  which  equals  64,000  Ibs.  for  a  bar 
having  i  square  in.  of  sectional  area,  which  would 
be  about  the  average  tensile  strength  of  first  quality 
steel. 

After  tensile  strength  is  found,  all  the  plates  are 
stamped  T.  S.  in  that  particular  batch,  and  under- 
neath stamp  64,000.  Sheets  not  stamped  should 
not  be  rated  at  more  than  48,000  Ibs.  T.  S. 

STEEL   AND    IRON 

Q._What  is  steel? 

A. — Steel  is  a  variety  of  iron  containing  from 
one-half  of  one  per  cent  to  one  and  a  half  of  one 
per  cent  of  carbon. 

Q._What  is  iron? 

A — Iron  is  a  metal,  the  most  abundant  and  the 
most  important  of  all.  It  contains  always 
impurities,  such  as  magnesia,  sulphur  and 
phosphorus.  It  is  hardly  anywhere  found  native, 
but  must  be  manufactured  from  ore.  Cast  z'rbn  is 
brittle  and  hard.  Wrought  iron,  obtained  by 
puddling,  is  softer  and  malleable. 

Q. — What  are  th£  principal  advantages  of  steel 
over  iron? 

A. — Greater  elasticity  and  hardness,  which  by 
tempering  may  be  increased  to  any  desired  degree. 


62  QUESTIONS    AND    ANSWERS 


POP  AND  LEVER  SAFETY  VALVES 

Q. — Of  what  use  are  safety  valves? 

A. — They  are  to  release  the  boiler  automatically 
of  all  steam  pressure  above  a  certain  point. 

Q. — Are  there  more  than  one  kind  of  safety 
valves? 

A. — Yes — the  old  lever  and* the  spiral  spring 
safety  valve. 

Qt — When  steam  is  heard  issuing  from  a  safety 
valve,  does  it  signify  danger? 

A. — No;  it  is  a  signal  of  safety.  It  shows  the 
valve  is  in  working  order  and,  if  properly  set  and 
adjusted,  it  is  a  sure  protection  against  trouble 

Q. — How  do  you  set  a  pop  safety  valve? 

A. — In  setting  the  valve  shown  on  page  63,  re. 
move  the  cap  H.,  and  turn  the  set  bolt  O  up  or 
down,  to  decrea  se  or  increase  the  pressure. 

Q. — How  is  the  amount  of  reduction  regulated? 

A. — Remove  the  set  screw  D  (Fig.  i)  from  the 
lower  part  of  the  case  M,  insert  a  pointed  instru- 
ment in  the  screw  hole,  and  with  it  turn  down  (to 
the  left)  the  set  ring,  increasing  the  amount  of 
.loss,  or  up  (to  the  right)  for  decreasing  the  amount. 
Then  replace  the  set  screw  which  holds  the  ring 
in  position. 


SAFETY    VALVE 


Fig.  i 


V  is  the  valve  nut  into 
which  O  is  screwed.  B  is 
the  valve.  N  is  the  upper 
cap  over  spring  casing  K 
inside  casing  M.  S  is  the 
upper  spring  cap,  R  the 
lower.  T  is  the  testing 
lever,  C  the  main  casing, 
Ethe  bolt  bushing,  F  the 
bushing  jam  nut,  A  the 
guide  for  valve  disc,  J  the 
guide  for  lower  valve  stem. 

Q. — How  large  a  loss  is  it  usual  to  have? 

A. — Three  or  four  pounds.  A  valve  can  be  set 
to  lose  less  than  half  a  pound  in  popping. 

Q. — What  new  device  is  there  for  deadening  the 
sound  of  the  pop  valve? 

A.— The  muffler  attachment.     (Fig.  2.) 

Q. — How  is  the  Muffler  Valve  adjusted? 

A. — It  can  be  adjusted  on  top  without  remov- 
ing from  the  dome.  In  order  to  adjust  either  the 
pressure  or  the  blow-down,  first  remove  the 
muffler  I ;  this  exposes  the  compression  screw  G, 
adjustable  nut  M,  crosshead  L,  locking  latch  O, 
and  check  nut  H.  By  loosening  the  check  nut  H 
and  screwing  down  the  compression  screw  G,  you 
increase  the  pressure,  and  the  reverse  for  lessening 
the  "pressure.  (As  .a  general  rule  from  1-16  to  % 
turn  will  change  the  pressure  of  valve  five  Ibs. 


64 


QUESTIONS    AND    ANSWERS 


ff 


either  way. )  By  raising  the  locking  latch  O  and 
screwing  down  on  the  adjusting  nut  M  one  notch 
you  will  reduce  the  blow-down  one  pound,  and  the 
reverse  increases  it  one  pound. 

A  base,  A1  valve  seat,  B 
valve,  C  spindle,  D  spring,  E 
follower,  F  F1  main  casting, 
F2  thread  hub,  G  compression 
screw,  H  check  nut,  I  muffler, 
J  the  regulating  ring,  J  J1 
lugs  on  ring,  K  parallel  rods, 
L  cross-head,  M  adjusting 
nut,  O  locking  latch. 

Q. — Give  proper  size  of 
safety  valve  for  a  boiler 
having  25  sq.  feet  of  grate 
surface,  allowing  for  70  Ibs. 
pressure? 

A. — For  each  foot  of  grate 
surface  22. 5  feet  boiler  heating 
surface  is  allowed ;  25  X  22. 5=562. 5.  For  the  water 
in  the  boiler  we  allow  8.33  (the  weight  in  Ibs.  of 
one  gallon),  which,  added  to  the  given  pressure, 
gives  78.33.  562.5  divided  by  78.33  equals  7.18 
sq.  inches  area,  or  a  3 -inch  diameter. 

Q. — How  would  you  figure  the  pressure  under 
a  3-inch  safety  valve  with  75  Ibs.  boiler  pressure? 

A. — Three  times  3  equals  9  inches,  times  .7854 
equals  7,068  area,  times  75  equals  530.1  Ibs. 

Q. — What  is  the  United  States  government  rule 
about  the  relative  areas  of  grate  and  safety  valve? 


SAFETY    VALVE  65 

A. — One  square  inch  area  of  lever  safety  valve 
to  2  square  feet  of  grate  surface. 

Q. — State  the  general  allowance  among  inspect- 
ors? 

A. — One  inch  area  of  safety  pop_valve  to  3 
square  feet  of  grate  surface. 

Q. — Find  area  of  a  pop  valve  3^  inches  in 
diameter?  (See  table  of  areas,  page  235.) 

A. — Multiply  diameter  by  itself  and  then  by 
decimal  .7854;  answer  is  the  area,  less  decimals. 

Q. — When  calculating  the  load  on  a  safety  valve, 
is  allowance  made  for  the  atmospheric  pressure  on 
top  of  valve? 

A. — No;  because  it  is  present  everywhere,  inside 
and  outside  the  boiler,  and  may  be  left  out  of  the 
calculation  entirely. 

Q. — Are  the  spring  safety  pops  calculated  when 
set? 

A. — No:  as  a  rule  they  are  set  by  a  test  steam 
gauge. 

Q. — What  is  done,  if  in  such  a  test^the  needle 
does  not  show  true  at  100  Ibs.  pressure? 

A. — It  is  pulled  off  the  pin,  and  then  put  back  in 
the  right  position. 

Q. — What  is  meant  by  a  strong  or  light  needle? 

A. — It  is  termed  strong  when  at  the  test  it  shows 
less  than  the  true  pressure,  and  it  is  called  light 
when  it  shows  more. 

Q.— What   is   it    that    keeps    the    face    of    the 


66  QUESTIONS    AND    ANSWERS 

valve  and  the  seat  in  line  (opposite)  and  causes 
the  rise  and  fall  to  be  even  and  true? 

A. — The  valve  spindle. 

Q. — What  is  the  point  of  contact? 

A. — Where  the  valve  and  its  seat  meet. 

Q. — At  what  angle  is  the  edge  of  the  valve  and 
its  seat  beveled? 

A. — At  an  angle  of  45  degrees. 

Q. — How  is  it  known  when  the  safety  valve  is  in 
good  working  order? 

A. — By  the  steam  and  gauge.  Let  the  steam 
pressure  rise  enough  to  just  move  the  safety — no 
more — and.  note  the  correspondence  between  the 
gauge  and  safety  valve. 

Q. — Is  there  another  way? 

A. — Yes — raising  the  valve  by  hand. 

Q. — How  do  you  find  the  exact  place  where  to 
place  the  ball  (weight)  on  the  long  lever  of  the 
safety  valve? 

A. — By  applying  the  laws  of  leverage.  (Page  241. ) 

Q. — How  do  they  apply  in  a  safety  valve? 

A. — The  bar  holding  down  the  valve  is  a  lever 
of  the  third  kind,  the  pivot  representing  the 
fulcrum,  the  valve  representing  the  power,  and  the 
ball  representing  the  weight.  (See  cut,  page  68.) 

Q. — Give  the  rule  for  calculating  the  distance 
from  the  fulcrum  at  which  a  given  weight  must  be 
set  to  cause  the  valve  to  blow  at  any  specified 
pressure. 


SAFETY    VALVE  67 

A.  —  i.  Multiply  the  area  of  the  valve  in  square 
inches  by  the  pressure  in  pounds  per  square  inch. 
Call  this  product  "number  i." 

2.  Multiply  the  weight  of  the  lever  in  pounds 
by  the  distance  in  inches  of  its  center  of  gravity 
from   the   fulcrum;   divide   the   product  by    the 
distance  in  inches  from  the  center  of  the  valve  to 
the  fulcrum  ;  add  to  the  quotient  the  weight  of  the 
valve  and  spindle.     Call  this  sum  "number  2." 

3.  Divide  the  distance  in  inches  from  the  center 
of  valve  to  fulcrum  by  the  weight  of  the  ball  in 
pounds,  and  call  the  quotient  "number  3." 

4.  Subtract  "number  2"  from  "number  i,"  and 
multiply  the  difference  by  "number  3";  the  prod- 
uct is  the  answer. 

Example:  Given  :  diameter  of  valve  4  inches  ; 
distance  from  fulcrum  to  center  of  valve  4  inches  ; 
weight  of  lever  7  Ibs.  ;  distance  from  fulcrum  to 
center  of  gravity  of  lever  15^  inches;  weight  of 
valve  3  Ibs.  ;  weight  of  ball  108.24  Ibs.  Blowing- 
off  pressure  75  Ibs. 

Area  of  4"  valves  =  12.566  square  inches 
75  X  12.566  =  942.45 


4  -f-  108.24  =  .0369 
942.45  —30.125  =912.325 
912.325  X  .0369  =  35.66  inches.    Ans. 

Q.  —  How  do  you  find  the  pressure  at  which  a 
safety  valve  will  blow  off  when  the  weight  and 
ita  position  are  known? 


68  QUESTIONS    AND    ANSWERS 

A.  —  Divide  the 
fulcrum  into  the 
length  of  lever, 
multiply  by  weight 
of  ball,  add  weight 
of  lever,  valve  and 
stem  and  divide  by 

^  Q£  ^^ 

Q. — How  is  the  total  weight  of  lever,  valve  and 
stem  found? 

A. — The  easiest  way  is  to  tie  the  stem  with  a 
string  to  the  lever  and  attach  a  spring  (scale) 
balance  to  the  lever  and  valve,  directly  over  the 
center  of  the  valve,  and  weigh  them  in  place. 

AUTOMATIC  EXTINCTION  OF   FIRE  BY   STEAM  AT  LOW 
WATER 

In  this  device,  recently  patented  in  Vienna,  a 
pipe  reaches  through  the  top  of  the  boiler  down  to 
low  water  mark,  so  that  steam  will  enter  it  as 
soon  as  the  water  falls  below  the  mark.  In  the 
upper  end  of  the  pipe  a  safety  fuse  is  melted  by 
the  steam,  opening  connection  with  a  second 
pipe,  which  leads  into  the  fife-box,  where  the 
steam  extinguishes  the  fire. 

The  fuse  being  a  ring  between  a  conical  valve 
and  its  seat,  the  valve  can  be  screwed  down  on 
the  valve  seat,  as  soon  as  the  fuse  is  melted  out, 
and  a  new  fuse  put'in  at  any  convenient  time. 


INJECTORS  69 

A  whistle  or  bell  is  easily  connected  with  the 
apparatus  to  give  alarm.  The  air  in  the  pipe  first 
mentioned  is  exhausted  through  a  stop-cock, 
after  the  boiler  is  heated. 


INJECTORS 

Q. — What  is  an  injector  and  its  use? 

A. — It  is  a  substitute  for  a  pump  and  is  used  in 
feeding  a  boiler  with  water.  ^ 

Q. — How  is  it  that  an  injector  forces  water  into 
a  boiler  against  the  pressure  of  the  steam  operating 
it? 

A. — The  water  and  steam  mingling  at  the  com- 
bining tube,  the  steam  jet  is  condensed,  con- 
verted into  a  water  jet.  This  water  jet  has  a  much 
smaller  cross  section  area  than  the  steam  jet  had, 
and  as  the  energy  of  the  steam  jet  is  retained 
entire,  a  greatly  increased  velocity  results. 

Q. — What  forces  the  boiler  check  valve  open? 

A. — The  pressure  of  the  water  in  the  delivery 
pipe. 

Q. — State  the  velocity  of  steam  passing  through 
an  inch  pipe  at  100  Ibs.  pressure? 

A. — Two  thousand  feet  per  second. 

Q. — Where  would  you  look  for  trouble  if  the 
injector  stream  broke  and  the  same  injector 
always  before  worked  well? 


M  N  rc  Tf  xnvO  l>00  O  O  -  "»  «^ 


INJECTORS  7* 

A. — At  the  water  and  steam  supply. 

Q. — Of  what  use  is  a  steam  nozzle? 

A. — It  is  for  the  actuating  steam  jets  to  pass. 

Q. — Where  is  the  combining  tube? 

A. — In  the  casing  of  the  injector  where  the 
steam  and  water  mix. 

Q. — Where  is  the  delivery  tube  of  an  injector 
and  what  is  its  use? 

A. — It  is  where  the  maximum  velocity  of  the 
stream  is  attained,  and  the  jet  overcomes  the 
back  pressure  from  the  boiler. 

Q. — Are  injectors  divided  into  classes;  if  so, 
state  how  many? 

A.— Yes;  they  are  divided  into  two  general 
classes,  the  lifting  and  non-lifting. 

Q. — Can  these  two  classes  be  subdivided? 

A. — Yes ;  they  may  be  divided  into  six,  namely, 
single  tube,  double  tube,  self-adjusting,  restarting, 
open  or  closed  overflow  injectors. 

Q. — Is  it  a  good  idea  to  turn  on  more  steam 
after  overflow  has  been  shut  off? 

A. — No;  it  will  cause  the  injector  to  break  the 
stream. 

Q. — State  some  of  the  principal  causes  that 
make  an  injector's  stream  break? 

A.— ^Not  enough  water  supply,  straws,  chips, 
mud,  cinders,  leaky  joints,  overheated  water,  bad 
strainers,  corrosion  in  the  injector  casing  and  low 
steam  pressure. 


72  QUESTIONS    AND    ANSWERS 

Q. — What  rules  are  used  for  determining 
the  proper  size  of  an  injector  for  different 
boilers? 

Rule  i.  For  Vertical  Tubular  Boilers — reduce 
all  dimensions  to  inches  and  multiply  the  circum- 
ference of  the  fire  box  by  its  height  above  the 
grate ;  multiply  the  combined  circumference  of  all 
the  tubes  by  their  length ;  next  subtract  from  the 
area  of  the  lower  tube  sheet,  the  area  of  all  the 
tubes  and  add  the  remainder  to  the  sum  of  the 
area  of  the  tubes  and  shell  and  divide  total  by 
144,  and  the  quotient  will  be  the  number  of  square 
feet  of  heating  surface. 

Rule  2.  For  Horizontal  Tubular  Boilers — reduce 
all  dimensions  to  inches  and  multiply  two-thirds 
of  the  circumference  of  the  shell  by  its  length; 
multiply  the  length  of  the  tubes  by  their  combined 
circumference;  next  subtract  from  two-thirds  of 
the  area  of  both  heads  the  combined  area  of  the 
tubes  and  add  the  remainder  to  the  sum  of  the 
tubes  and  shell,  divide  total  by  144,  etc. 

Rule  3.  For  Water  Tube  Boilers.— Proceed  to 
find  the  area  of  all  heating  surfaces  exposed  to  the 
radiation  of  gases  from  the  furnace  of  boiler,  and 
if  area  is  in  inches,  divide  by  144,  etc.,  as  above. 

After  finding  the  heating  surface,  as  per  rule 
i,  2  or  3,  divide  by  30  (see  page  150)  to  get  the 
horse  power,  and  allow  10  gallons  of  water  per 
hour  for  each  horse  power. 


FEED   PUMPS  73 

would  be  a  short  rule  then? 
A. — If  H.  P.  is  known,  multiply  number  by  10 
to  find  number  of  gals,  of  water  the  injector  should 
deliver  per  hour.     If  H.  P.  is  not  known,  multi- 
ply number  of  sq.  feet  of  heating  surface  by  3. 


FEED  PUMPS 

Q. — Name  Khe  different  kinds  of  pumps  used 
flaily  for  boiler  feeding,  etc.  ? 

A. — Single  action,  with  two  valves,  receiving 
and  discharging;  the  double  action,  with  two  or 
more  discharging  valves.  The  latter  receives  and 
discharges  water  at  both  ends  of  water  cylinder 
and  has  a  steam  cylinder  attached  to  work  the 
pump.  The  duplex  is  a  combination  of  two 
double  action  pumps  all  cast  together  side  by  side. 

Q. — What  are  the  relative  proportions  of  steam 
and  water  cylinders  of  feed  pumps? 

A.— The  steam  cylinder  is  1-3  larger  in  diameter 
than  the  water  cylinder. 

Q. — In  setting  up  a  steam  pump,  how  is  it 
leveled?  • 

A. — By  leveling  the  discharge  valve  seat  length- 
wise and  crosswise. 

Q. — Give  rule  to  find  area  of  a  steam  piston  in 
connection  with  a  pump? 

A. — Multiply  the  area  of  water  plunger  by  2. 

Q. — Of  what  are  pump  valves  made? 


74  QUESTIONS    AND    ANSWERS 

A. — Hard  or  soft  rubber,  brass  and  sometimes 
vulcanized  fiber  and  wood. 

Q. — Can  you  give  a  short  rule  to  find  the  sizes 
of  steam  pipes  for  cylinders? 

A.— Divide  the  area  of  steam  piston  by  64  for 
steam  pipe,  and  by  32  for  exhaust.  Divide  the 
area  of  plunger  by  3  for  discharge  pipe,  and  by  2 
for  suction  pipe. 

Q. — Suppose  you  had  a  duplex  pump,  size  8  in. 
water  by  10  in.  steam  by  12  in.  stroke  and  3  in. 
diameter  plunger  rod,  making  100  ft.  piston  travel 
per  minute,  how  many  gallons  of  water  would 
the  pump  deliver,  having  full  supply  of  water? 

A. — First  find  the  area  of  plunger  face — 8  times 
Sin.  equals  64,  multiplied  by  .7854  equals  50.2656, 
by  12  in.  stroke  equals  603.1872,  by  4  cylinder  ends 
equals  2412.7488  cubic  in.  Now  subtract  the  cubic 
contents  of  3  in.  diameter  plunger  rod  12  in. 
stroke  in  one  end  of  each  water  cylinder  from  the 
total  cubic  inches  and  divide  by  231,  which  gives 
gallons  for  one  stroke,  4  ends.  This  multiplied 
by  100  piston  travel  gives  total.  Three  multiplied 
by  3  equals  9,  by  .7854  equals  7.0686,  by  12  equals 
85.032,  by  2  equals  170.064,  subtract  from  2412.7488 
equals  2242.6840,  divided  by  231  cubic  inches  in  a 
gallon  equals  9. 708  gals,  one  stroke,  multiplied  by 
100  equals  970.8  gals,  per  minute.  This  rule  holds 
good  on  other  pumps. 

Q. — Give  quick  rule  to  find  quantity  of  water 


FEED    PUMPS  75 

pumped  in  one  minute,  pump  making  100  ft.  of 
piston  speed  per  minute? 

A. — Multiply  the  diameter  of  the  water  plunger 
by  itself,  then  multiply  the  product  by  4.  Answer 
gives  gallons  for  one  pump ;  if  for  two* pumps  mul- 
tiply answer  by  2  and  so  on. 

Q. — How  could  the  horse-power  be  found 
necessary  to  pump  water  to  a  given  height? 

A. — Multiply  the  total  weight  of  water  in  pounds 
by  the  height  in  feet  and  divide  by  16,500.  This 
allows  for  water  friction  and  steam  loss. 

Q.— How  are  the  steam  valves  of  duplex  pumps 
set  and  adjusted? 

A. — Remove  the  valve  chest  cover,  place  the 
rocker  arm  plumb  (reach  arm),  then  see  how  the 
valve  on  opposite  cylinder  is  for  lead ;  if  equal  at 
both  ends,  the  valve  is  set,  if  not,  adjust  the  jamb 
nuts  to  suit.  Do  the  same  on  the  other  pump. 

Q. — Does  the  duplex  pump  exhaust  its  steam 
through  the  same  port  that  it  enters  and  thence 
through  the  cavity  under  the  valve  to  the  exhaust 
chamber  as  in  the  common  slide-valve  engine? 

A. — No.  It  has  a  separate  steam  and  exhaust 
port  at  each  end.  (See  cut,  page  76.) 

Q.— How  does  it  work? 

A. — The  piston  covers  and  closes  the  exhaust 
before  it  reaches  the  end  of  its  stroke,  and  the 
steam  left  in  the  cylinder  acts  as  a  cushion.  At 
the  end  of  stroke  the  steam  valve  opens  and  the 


76 


FEED    PUMPS 


77 


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17.  "  Tongue  Spring. 
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21.  Steam  Cylinder  Foot. 

22.  Exhaust  Outlet. 

23.  Piston  Rod. 
24.  Valve  Rod  Head  Pin. 

25.  Rod  Link  (long  &  short; 

26.  Long  Lever. 
37.  Short  Lever. 

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78  QUESTIONS    AND    ANSWERS 

live  steam  forces  the  piston  back.     The  same  at 
both  ends. 

Q. — Why  does  the  piston  with  the  long  lever 
move  in  the  same  direction  as  the  opposite  valve, 
while  the  other  piston  with  short  lever  and  the 
opposite  valve  rod  move  in  opposite  directions  to 
each  other? 

A. — The  lever  last  mentioned  (indirect  motion) 
starts  the  opposite  piston  on  the  reverse  stroke, 
and  this  piston  on  reaching  the  end  of  the  stroke 
opens  the  valve  for  the  other  piston  to  reverse. 

Q. — Why  is  this  arrangement  made  so? 

A.  — Because  it  is  necessary  to  secure  the  reversal 
of  the  pumps,  which  could  not  be  done  in  any 
other  way  as  simple. 

Q. — What  gives  the  most  trouble  about  a 
pump? 

A. — Leaks,  in  one  way  or  another. 

Q. — How  large  a  vacuum  can  be  maintained  con 
veniently  in  a  suction  pipe? 

A. — About  28  inches  by  gauge. 

Q. — How  large  a  vacuum  should  there  be? 

A. — There  should  be  3  or  4  more  inches  of  vac- 
uum than  feet  of  lift. 

Q. — Suppose  the  suction-pipe  was  air-tight,  and 
the  vacuum  was  too  low,  what  would  generally  be 
the  cause? 

A. — Leaky  valves,  or  a  leaky  plunger,  or  a  leaky 
Stuffing-box,  or  a  cracked  cylinder. 


FEED    PUMPS  79 

Q. — What  is  the  proper  size  of  the  suction-pipe? 

A. — The  full  size  of  the  opening  in  the  pump. 

Q. — Would  a  leaky  water  end  of  a  pump  cause 
any  unnecessary  waste  of  steam? 

A.  — Yes ;  a  pump  would  have  to  work~at  greater 
speed  to  keep  the  boiler  supplied  with  water,  than 
otherwise  required,  and  this  means  a  waste  of 
steam. 

Q. — Upon  investigation  what  would  you  find  to 
be  the  trouble? 

A. — The  water  end  improperly  packed  or  no 
packing. 

Q. — Suppose  the  pump  used  a  good  deal  of 
steam  and  still  went  very  slowly,  causing  great 
friction,  to  what  would  you  lay  the  trouble? 

A. — To  the, pump  being  packed  too  tightly. 

Q.  — How  should  the  rings  be  fitted  to  prevent 
the  friction? 

A.  — Cut  the  ring  joints  a  little  short  to  allow  for 
expansion  when  wet  or  under  pressure. 

Q.  — How  would  you  try  the  pump  to  know  that 
the  packing  is  in  good  order? 

A.  — Close  the  delivery  valve  near  the  pump,  let 
plunger  make  a  stroke  up  and  down.  If  then  the 
pump  stops  of  its  own  accord  the  plunger  is  well 
packed. 

Q. — Is  there  any  danger  of  bursting  the  pipe? 

A. — No,  for  the  pipe  and  valve  should  be  able  to 
withstand  the  pressure. 


80  QUESTIONS    AND    ANSWERS 

Q.  — Is  the  pressure  greater  in  the  pipe  than  in 
the  boiler;  if  so,  what  causes  it? 

A. — Yes,  as  there  is  more  area  in  the  steam 
cylinder. 

Q.  — How  many  valves  has  a  duplex  pump,  and 
how  many  stories? 

A. — The  duplex  pump  has  eight  valves  and  two 
stories,  four  valves  to  each  story,  one  story  above 
the  other.  Larger  pumps  have  more  in  proportion. 

Q. — Where  are  the  receiving  valves  located  in  a 
3x4x6  inch  duplex,  also  the  discharge  valves? 

A. — The  receiving  or  suction  are  the  lower  set 
and  the  discharge  the  upper  set. 

Q. — How  would  you  partition  off  the  valves  in 
the  water  end  of  a  double-acting  pump? 

A. — Place  the  partition  between  the  suction 
valves  only. 

Q. — How  many  ports  has  each  steam  cylinder 
of  a  duplex  pump?  name  them. 

A. — There  are  five,  namely,  two  steam,  two 
exhaust  and  one  outlet  port  to  the  atmosphere. 

Q. — How  wide  are  the  steam,  exhaust  and  out- 
let ports  of  a  duplex  pump  3x4x6  inches  and  how 
thick  are  the  dividing  ribs? 

A. — The  steam  and  exhaust  ports  are  7-16  of  an 
inch,  the  outlet  (in  the  center)  is  9-16,  and  the  ribs 
^  inch  each. 

Q. — How  long  is  the  exhaust  cavity  in  the  middle 
of  steam  slide  valve? 


FEED    PUMPS  8l 

A. — It  is  i  and  9-16  inches  long. 

Q. — How  long  are  the  two  faces  at  each  end  oi 
valve? 

A. — They  are  each  the  same  length  as  exhaust 
cavity. 

Q. — How  much  lap  has  the  valve  at  each  end 
over  the  steam  ports  when  in  central  position? 

A. — Three-sixteenths  of  an  inch. 

Q. — How  much  lap  has  the  exhaust? 

A. — None;  the  valve  just  seals  the  two  exhaust 
ports. 

Q. — Why  do  large  pumps  have  many  small 
water  valves? 

A. — So  the  loss  of  water  will  not  be  so  great  in  the 
rise  and  fall  of  the  valves  when  the  pump  is  working. 

Q. — How  is  a  vacuum  created  in  a  pump 
cylinder? 

A. — There  is  not  a  real  vacuum  at  any  moment ; 
the  water  follows  the  piston  as  fast  as  it  moves, 
driven  by  the  14.7  Ibs.  per  sq.  in.  pressure  of  the 
atmosphere. 

Q. — To  what  height  would  the  water  follow,  the 
piston? 

A.— To  the  height  of  33  feet.  At  this  point  the 
column  of  water  in  the  pipe  would  have  the  same 
weight  as  a  column  of  the  atmosphere  with  the 
same  cross  section  area. 

Q. — Why  is  a  check  valve  placed  near  the  boiler? 

A. — To  prevent  the  water  in  the  boiler   from 


82 


QUESTIONS    AND    ANSWERS 


being  forced  back  onto  the  pump  at  the  end  of  each 
stroke. 

Q. — What,  if  there  were  no  check  valve? 


^Btil  Check  Valye.  Horizontal  Check  Valve- 

A. — The  pump  could  be  run,  but  the  discharge 
valve  would  seat  too  hard  and  would  wear  out  too 
soon. 

Q.--What  is  done  when  the  check  valve  needs 
repairing? 

A. — The  gate  valve  between  the  check  valve 
and  the  boiler  is  closed. 

Q. — Are  angle  check  valves  and  vertical  check 
valves  used  with  boilers? 

A. — Rarely ;  they  are  mostly 
used  for  connecting  a  steam 
heating  system  to  the  traps  in 
the  boiler  room. 

Q. — How  much  lift  should  a 
check  valve  have? 

A. — Enough  to  give  an  area 
of  opening,  equal  to  the  area  of 
the  feed  pipe. 

Q.— Is  it  well  to  give  it  a 
larger  lift? 


Sectional. 

"  Clip"  Gate  Valve 


FEED    PUMPS  83 


Angle  Check  Valve.         Vertical  Check 
Valve. 

A.— No ;  too  much  lift  wears  valve  and  seat 

Q. — What  is  the  use  of  the  pet  cock? 

A. — If  the  pump  is  in  good  order,  the  pet  cock 
will  show  full  stream  at  forcing  and  weak  at  suc- 
tion. It  shows  tank  or  hydrant  pressure  both 
strokes,  when  receiving  valve  is  held  open  by  dirt, 
etc.  It  shows  boiler  pressure  both  strokes  when 
check  and  discharge  valves  do  not  work  properly. 

Q. — What  is  the  air  chamber's  duty? 

A. — The  elasticity  of  the  air  in  it  renders  the 
pressure  and  flow  practically  uniform,  notwith- 
standing the  intermittent  action  of  the  force.  It 
furnishes  what  in  electricity  would  be  called  a 
constant  potential  service.  It  also  renders  the 
seating  of  the  valves  more  even. 

Q. — What  are  the  features  of  a  Fire  Engiite? 

A. — A  fire  engine  consists  essentially  of  a  pair 
of  single-action  suction  and  force  pumps.  The 
boilers  are  tubular,  of  sufficient  capacity  to  work 
the  pumps  500  strokes  per  minute.  The  working 
pressure  of  steam  is  usually  80  to  100  Ibs.  per 
square  inch. 


THE  ARTESIAN 
PUMP 

The  engine  part  of  the 
artesian  pump  shown  in 
the  cut,  is  a  common  ver- 
tical slide  valve  engine  in 
its  cylinder  parts. 

The  figures  indicate  the 
parts  as  follows: 

1.  Steam  Cylinder. 

2.  Steam  Cylinder  Head. 

4.  Steam  Piston  Head. 

5.  Follower  Head. 

6.  Inside  Piston  Ring. 

7.  Outside  Piston  Rings 

8.  Adjusting  Screw. 

9.  Jam  Nut. 

10.  Adjusting  Spring. 
,5    11.  Cap   Screws    for    Fol- 
lower. 

12  A,  B.  Piston  Rod. 
*  13.  Brass  Piston  Rod  Nuts. 

14.  Steam  Slide  Valve. 

15.  Steam  Chest. 

16.  Steam  Chest  Cover. 

17.  Upper  Stem  Gland, 

18.  Lower  Stem  Gland. 

19.  Gland  Studs. 

20.  Steam  Valve  Stem. 

24.  Stem  Guide  on  Cylin- 

der. 

25.  Brass  Jam  Nut. 

26.  Brass  Split  Nut. 

27.  Brass  Tappet  Head. 

28.  Tappet  Head  Bolt. 

29.  Stem  Link. 

31.  Fulcrum  Bolt. 

32.  Stem  Guide. 

33.  Stand. 

34.  Piston  Rod  Gland. 
36.  Swinging  Arm. 
38.  Crosshead  Link. 

40.  Crosshead  with  Bolts. 

41.  Crosshead  Jam  Nuts. 

46.  Suction  Flange  in  the 

Base. 

47.  Discharge  Flange. 

48.  Hinge  Bolt  and  Nut. 
65.  Base      Stuffing     Box 

Gland. 


STEAM  PUMP  GOVERNOR 


DESCRIPTION. — The  upper  wheel  i  jn  yoke  is  the 
lock  nut.  Turn  it  to  the  left;  then  turn  lower 
wheel  2  to  the  right,  which 
raises  and  opens  the  double 
steam  valve  8;  when  partly 
open,  open  the  throttle  valve 
and  start  the  steam  pump. 
Now  close  angle  ^alve  4  and 
open  globe  valve  5.  This  lets 
the  main  water  pressure  on  the 
piston  6  and  spring  3  in  brass 
water  cylinder  7.  Now  regu- 
late by  screwing  up  or  down  on 
wheel  2  until  the  water  pressure 
gauge  shows  pressure  desired 
to  carry ;  then  set  in  place  by 
turning  wheel  i  to  the  right 
until  up  against  bottom  end  of 
the  piston  rod. 

To  OPERATE. — In  starting  or 
stopping  the  pump  do  it  with    PUMP  GOVERNOR 
the  main  steam  throttle.      Do    not   change    the 
adjustment  of   the  governor.     In  starting,  close 
globe  valve  5  and  at  the  same  time  open  angle 
valve  4.    As  soon  as  started,  close  angle  valve  4, 


86  PUMP    GOVERNOR 

open  globe  valve  5  and  pump  will  hold  the  pressure 
at  which  it  is  set. 

PACKING  GOVERNOR,  ETC. — Pack  the  valve  rod  as 
light  as  you  can  and  screw  stuffing  box  nut  down 
lightly  with  thumb  and  finger,  just  enough  to 
stand  the  strain.  Do  not  use  wick  packing,  but 
some  good  sectional,  square  or  round  packing. 

To  CLEAN  AND  OIL  GOVERNOR. — Once  a  month 
run  the  pump  by  the  throttle,  shut  off  both  valves 
4  and  5,  then  open  union  9,  take  off  water 
cylinder  cap  n,  take  out  piston  6,  also  stem  and 
steel  spring  3,  wipe  out  the  cylinder  7,  clean  piston 
head  6,  and  oil  them  with  some  good  oil  that  will 
not  gum.  If  governor  is  kept  clean  and  attention 
paid  according  to  directions  no  trouble  will  arise. 

To  CONNECT. — Place  governor  between  the  steam 
chest  and  throttle  valve  so  it  will  stand  plumb; 
connect  bottom  outlet  flange  or  screw  with  steam 
pipe  on  steam  chest,  then  connect  the  boiler  pipe  to 
inlet,  placing  throttle  in  most  convenient  place. 
Use  short  nipples  so  as  to  place  governor  as  close 
to  steam  chest  as  possible, 

To  CONNECT  WATER  PART. — Tap  the  discharge 
main  or  pipe,  if  horizontal,  on  the  side  for  J^  inch 
pipe,  run  pipe  up  about  a  foot  higher  than  top  of 
pipework  of  governor,  then  over  to  it  and  down 
and  connect  to  quarter-inch  valve  on  top  of  pipe- 
work over  governor.  If  for  two  governors  on 
pumps  discharging  into  same  main  tap,  the  same  as 


PUMPS  *       87 

\0 

for  single  governor  and  run  up  and  over  between 
governors,  then  put  on  a  "T,"  and  run  to  right 
and  left  till  over  pipework  above  each  governor 
and  connect.  If  the  pulsation  of  pump  is  noticed 
it  can  be  avoided  by  partly  closing  globe  valve  5. 
Never  connect  close  to  air  chamber.  Insert  a 
short  piece  of  pipe  in  drip  "T"  12  at  bottom  of 
brass  cylinder  to  reach  the  floor. 

DOUBLE   ACTION    WATER    PUMP    WITH 

ROLLING  VALVES 
(See  page  88) 

A  double  action  water  pump,  built  in  two 
pieces.  A,  the  upper  or  main  part,  contains  the 
delivery  valves  c,d,  and  the  pump  barrel  c,  which 
is  made  of  a  seamless  drawn  brass  tube.  (Fig.  2.) 

The  lower  part  contains  the  chamber  B,  to 
which  the  suction  pipe  is  connected,  and  the 
suction  valves  a,  b.  It  is  bolted  to  A  by  bolts  e,  f . 

The  plunger,  D,  is  provided  with  two  reverse 
cup  leathers.  E,  the  plunger  rod,  passes  through 
the  stuffing  box  F. 

The  downward  stroke  of  D  opens  the  two 
valves  a  and  c,  while  it  closes  b  and  4.  The 
upward  stroke  acts  in  the  opposite  sense. 

The  deep  well  plunger,  Fig.  i,  consists  of  the 
brass  pump  cylinder  A,  the  pump  case  B,  the  air 
barrel  D,  and  the  water  pipe  E  connecting  pump 
to  stuffing  box ;  c  is  the  suction  valve,  b  the  deliv- 
ery valve,  f  the  suction  strainer. 


88 


THE  BOURDON  STEAM  SPRING  GAUGE 


VIEW    OF    INNER    PARTS 

DESCRIPTION. — A  brazed,  tempered-brass  tube, 
bent  in  an  almost  complete  circle,  has  the  open 
end  attached  to  one  arm  of  a  siphon  pipe,  while 
its  closed  end  is  fastened  to  a  lever.  The  steam 
pressure  on  the  water,  in  the  pipe  and  tube,  tends 
to  straighten  the  tube  or  spring  (by  pressing  more 
against  the  outer  curve  than  the  inner),  moving 
the  lever,  the  long  arm  of  which  turns,  with  its 
toothed  arch,  the  hand  of  the  dial,  indicating  the 
pressure  per  sq.  inch  of  boiler. 

Q. — Why  is  water  kept  in  the  spring  and  siphon? 

A. — A  direct  contact  with  steam  would  take  the 
temper  out  of  the  tube. 

Q. — How  is  a  vacuum  gauge  constructed? 
89 


90  QUESTIONS    AND    ANSWERS 

A. — It  has  a  lighter  spring  and  it  acts  in  the 
reversed  sense  as  the  atmospheric  pressure  tends 
to  bend  it  more,  the  less  pressure  there  is  inside, 
or  in  other  words,  the  greater  the  suction.  The 
dial  plate  is  graduated  to  register  30  inches  of 
vacuum  to  equalize  15  Ibs.  of  atmospheric  pres- 
sure or  a  column  of  mercury  of  36  inches. 

Q. — Explain  the  compound  ammonia  gauge? 

A.— It  is  the  same  ^style  as  a  steam  gauge,  only 
the  spring  is  of  steel  tubing  and  the  graduation  on 
the  dial  is  to  show  both  ways  from  zero  mart .  All 
figures  above  show  pressure  and  all  below  show 
vacuum. 

Q. — Why  is  the  ammonia  gauge  spring  made  of 
steel  instead  of  brass? 

A. — Because  the  ammonia  destroys  brass,  while 
steel  is  not  affected  by  it. 

Q.— Are  there  two  springs  in  the  compound 
ammonia  gauge? 

A. -.-No;  it  is  so  named  because  it  shows  either 
vacuum  or  pressure  on  the  same  dial  with  the 
same  needle. 

Q. — What  is  a  duplex  gauge? 

A. — It  has  two  springs  and  two  needles,  one 
showing  the  excess  pressure,  and  the  other  train 
pipe  pressure.  They  are  used  on  locomotives  only. 


THE  LUBRICATOR 

Q. — Of  what  use  is  a  lubricator? 
A. — It  supplies    the  valve,   piston  and  cylinder 
with  oil  automatically  after  the  drop  feed  is  set. 


CONNECTION 


Q.— How  many  different  styles  of  lubricators  are 
there  in  use? 

A. There  are  three — single  feed  for  stationary 

91 


92  QUESTIONS   AND    ANSWERS 

engines,  double  feed  for  compound  and  locomotive 
engines,  and  triple  feed  for  triple  expansion,  and 
locomotive  engines  and  air  pump. 

Q. — How  does  a  lubricator  do  its  work? 
,  A.— As  seen  in  the  cut,  by  the  condensed  water 
passing  down  the  center  water  pipe  from  the  con- 
dense chamber  to  the  bottom  of  the  oil  reservoir, 
forcing  the  oil  to  the  top  and  down  the  oil  pipes 
to  and  through  the  feeder  valves  C,  C.  After 
passing  the  feeder  valves,  the  oil  floats  up  through 
the  water  in  the  sight  feed  glass  and  on  reaching 
its  surface  is  carried  off  horizontally  through  the 
choke  plug  (P)  by  steam  from  pipe  E. 

Q.— How  is  the  lubricator  attached  to  the 
system? 

A. — Connect  its  top  to  the  live  steam  pipe  and 
the  feed  pipe  further  down. 

Q. — What  precaution  should  be  had  after 
attaching? 

A. — The  passages  and  connections  of  the  lubri- 
cator should  be  blown  out  with  steam. 

Q. — How  is  a  lubricator  filled? 

A.— Close  all  the  feeder  valves  C,  C,  also  the 
live  steam  connection,  then  open  blow-out  valve 
D,  and  fill  through  filler  plug. 

Q. — How  is  the  feed  stopped  and  started? 

A. — By  closing  and  opening  the  valves  C,  C. 

Q. — Supposing  the  lubricator  ran  empty  how 
would  you  refill  it? 


THE    LUBRICATOR 


93 


A.  —  Close  feeder  valve  C  and  live  steam  con- 
nection ;  open  blow-off  D  ;  open  filler  plug  and  as 
the  water  passes  out,  fill  in  with  oil. 

Q.  —  After  filling  what  do  you  do? 


A. — First,  close  drip  D,  screw  filler  plug  in  Jtight, 
open  live  steam  connection  fully,  then  regulate  oil 
flow  with  valves  C,  C. 

Q.  —Are  the  valves  B,  B  ever  closed? 

A.  — No,  except  when  a  feed  glass  is  broken. 

Q.-r-What  is  to  be  done,  when  a  glass  breaks? 

A. — Close  valves  C,  Cand  B,  B;  unscrew  plug  of 
top  bracket,  loosen  packing  nuts  and  remove  old 


94  QUESTIONS    AND    ANSWERS 

glass.  Insert  the  new  glass,  and  fasten  nuts  and 
valves,  etc. 

Q. — Is  it  well  to  reuse  old  gaskets? 

A.— It  is  not. 

Q. — Is  there  any  difference  between  the  single, 
double  and  triple  lubricators? 

A. — Not  in  principle  or  operation. 

Q. — Do  all  lubricators  work  alike? 

A. — No,  the  down  feed  lubricator  dispenses  with 
the  water  in  the  feed  glass. 

Q. — How  much  oil  should  be  fed  through  a 
lubricator  for  an  engine  working  heavily? 

A. — That  depends,  of  course,  on  the  quality  of 
the  oil,  and  also,  of  course,  on  the  condition  of  the 
engine.  For  heavy  work  2-5  drops  a  minute,  for 
light  work  1-4  drops. 

Q. — What  care  should  be  taken  in  filling  a 
lubricator? 

A. — No  foreign  matter  must  be  allowed  to  get 
in.  The  opening  in  the  feed  nozzle  is  so  small 
that  almost  anything  would  clog  it. 

Q. — How  large  is  the  opening? 

A. — It  is  3-32  of  an  inch. 

Q. — How  is  the  feed  nozzle  cleared  of  clogging 
matter? 

A. — By  shutting  off  the  live  steam  connection, 
opening  the  blow-off  and  then  opening  the  feed 
valve  to  allow  the  back  pressure  to  pass  through 
the  opening. 


THE   LUBRICATOR  95 

O 

Q. — How  is  the  choke  plug  cleared  of  clogging 
matter? 

A. — In  the  same  way.  The  back  pressure  will 
force  the  matter  into  the  feed  glass. 

Q. — How  large  is  the  opening  in  the  choke  plug? 

A. — It  is  3-64  of  an  inch. 

Q. — How  can  it  be  decided  whether  this  opening 
is  of  the  right  size? 

A. — Start  the  engine.  Then  regulate  the  oil 
feed  in  the  glass,  counting  the  number  of  drops  in 
one  minute.  Then  shut  the  throttle  of  the  engine 
and  notice  quickly  whether  the  number  of  drops 
changes.  The  number  will  not  change  if  the 
opening  is  of  the  proper  size. 

Q. — Is  it  harmful  to  use  more  oil  than  needed? 

A. — Yes.  It  clogs  up  the  exhaust  pipe  of  the 
engine,  decreasing  its  opening.  The  increase  in 
pressure  necessary  for  exhausting  through  a 
clogged  exhaust  pipe  means  larger  coal  consump- 
tion. Besides,  it  is  a  waste  of  oil. 

Q. — Is  it  well  to  feed  both  valve-oil  and  engine- 
oil  through  a  lubricator?  . 

A. — No.  The  mixing  impairs  the  lubricating 
properties  of  the  oils.  Only  valve-oil  should  be 
used  for  engine  cylinders. 


THE    ENGINE 

THE  COMMON  SLIDE  VALVE 

DESCRIPTION. — When  the  piston  is  at  either  end 
of  the  cylinder,  the  steam  port  at  that  end  is  open 
a  fraction  of  an  inch  (lead) ;  the  steam  enters 


and  starts  the  piston  on  its  travel,  the  port  opening 
wide  and  admitting  the  steam  freely.  The  valve 
travels  in  the  opposite  direction.  When  the  piston 
has  traveled  ^  or  so  of  its  stroke  (according  to 
the  lap  on  the  valve)  the  slide  closes  the  steam 
port,  so  that  during  the  remainder  of  the  stroke 
no  more  steam  enters  on  that  end  of  the  cylinder. 
The  steam  present  expands,  therefore,  as  long  as 
the  piston  keeps  moving  in  the  same  direction. 
At  the  moment  when  the  piston  reaches  the  other 

end  of  the  cylinder,  the  steam  port  there  opens 
96 


THE   ENGINE  97 

slightly  (lead),  the  entering  steam  pushes  the 
piston  back  and  the  expanded  steam  on  the  other 
end  of  the  piston  escapes  through  the  exhaust 
cavity  of  the  valve,  which  at  that  moment  con- 
nects the  steam  port  with  the  exhaust  port,  and 
disconnects  them  again  when  only  enough  steam 
is  left  to  serve  as  a  compression  at  the  point  from 
which  we  started.  The  operation  is  the  same  at 
both  ends  of  the  cylinder. 

Q. — How  would  you  proceed  to  set  a  common 
slide  valve? 

A. — See  that  valve  covers  both  steam  ports 
equally,  the  crank  pin  at  dead  center,  heavy  side 
of  eccentric  up  or  at  right  angle  with  the  crank 
pin,  rocker  arm  plumb,  at  center  of  'travel,  and 
all  connections  close  fit ;  move  the  eccentric  around 
on  the  shaft  in  direction  engine  is  to  run,  until  the 
valve  has  proper  lead,  say  1-16  of  an  inch,  then 
tighten  eccentric  with  set  screws,  turn  crank  pin  to 
opposite  dead  center  and  see  how  the  lead  is  at  the 
opposite  port.  If  equal  the  valve  is  set;  if  not, 
divide  the  difference  by  adjusting  the  length  of  the 
valve  rod  and  readjusting  the  eccentric. 

Q. — Is  the  common  slide  much  used? 

A. — Yes,  in  the  cheaper  forms  of  steam-engines, 
compressed-air  engines,  in  some  air-compressors, 
and  in  seme  compressed-air  ice  machines. 

Q. — How  is  the  length  of  the  valve  stem  and  of 
the  eccentric  rod  found? 


98 


THE    ENGINE 


99 


t  of  Common  Slide 

PPOSITE  PAGE 

RRESPONDING  PARTS 

Engine  Showing  Over  or 
Eccentric  Straps. 
"  Rod. 
4  Bushing. 
Valve  Cross  Head. 
"  "  "  .  Guide' 
Valve  Stem. 

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100 


QUESTIONS    AND    ANSWERS 


A. — Place  the  valve  in  the  middle  of  its  seat.  In 
this  position  the  rock  arm  is  vertical.  The  dis- 
tance A  between  a  vertical  line  drawn  through  the 
center  of  the  rock  shaft  and  a  vertical  line  through 
the  center  of  the  valve  is  the  length  of  the  valve 
stem.  The  distance  B  between  the  central 


vertical  of  the  rock  shaft  and  a  vertical  drawn 
through  the  center  of  the  main  shaft  is  the  length 
of  the  eccentric  rod. 

Q. — How  is  a  single  eccentric  engine  reversed? 

A. — Remove  the  valve  chest  cover,  measure  lap 
and  lead,  loosen  the  eccentric  and  move  it  around 
the  shaft  to  a  position  where  the  valve  will  show 
exactly  the  same  as  before.  Then  fasten  the 
eccentric  with  the  set  screws  in  position  and  cover 
the  valve. 

In  the  cut  above  position  Ei  shows  the  engine 
running  over  forward.  By  bringing  the  eccentric 
into  position  E2,  the  engine  is  reversed,  running 
under  backward.  Further  adjustments  can  then 
be  made  by  repeatedly  trying  the  engine  from  one 
dead  point  to  the  other. 


TIIJE    ENGINE 


Q.  —  How    would  you  reverse  the  motion  of  a 

common  slide  valve  engine? 

A.  —  Set  the  crank  pin  on  dead  center,"  remove 
the  valve  chest  cover  and  notice  the  amount  of 
lead  at  steam  edge  of  valve.  Then  -loosen  the  set 
screw  or  key  of  the  eccentric  and  turn  it  around  on 
the  shaft  in  the  same  way  it  has  been  running 
until  the  valve  has  reached  the  end  of  its  travel  ; 
keep  moving  the  eccentric  until  it  has  the  same 
lead  as  before,  then  tighten  the  set-screw. 

The  dotted  circles  in  the  cut  on  page  100  indi- 
cate the  positions  of  eccentric  other  than  plumb. 

Q.  —  How  is  a  single  eccentric  slide  valve  rocker 
arm  engine  converted  into  a  reversible  engine? 

A.  —  If  the  valve  has  neither  lap  nor  lead,  it  can 
be  done  by  putting  another  wrist  pin  in  the  rocker 
arm,  above  the  rock  shaft  center.  But  if  the 
valve  has  outside  lap,  then  another  eccentric  must 
be  put  on,  and  both  eccentric  rods  hooked  on  —  in 
their  turn,  according  as  the  engine  is  to  run  —  to 
the  same  wrist  pin  placed  below  the  center  of  the 
rock  shaft. 

Another  way  is  to  use  the  link  motion,*  as  in  a 
locomotive  engine. 

Q.  —  Which  leads,  the  crank  pin  or  the  eccentric? 

A.  —  The  eccentric.     (See  page  116.) 

Q.  —  At  what  angle  does  the  highest-pitch  line  of 
an  eccentric  lie  to  the  level  of  the  crank  pin  at 
dead  center? 


«;       QUESTIONS    A-NL»    ANSWERS 

A. — About  120  degrees. 

Q. — What  is  initial  pressure? 

A. — Initial  pressure  signifies  the  pressure  pres- 
ent in  the  cylinder  of  an  engine  at  the  beginning 
of  its  stroke. 

Q. — Explain  terminal  pressure? 

A.  — Terminal  pressure  is  in  the  cylinder  of  an 
engine  at  the  end  of  the  stroke  of  piston  if  the 
exhaust  valve  does  not  open  until  the  stroke  is 
finished. 

Q._What  is  meant  by  wire-drawn  steam? 

A.  — The  operation  of  reducing  the  steam  pres- 
sure between  the  boiler  and  the  cylinder. 

LEAD   AND   LAP 

Q. — What  is  pre-admission  or  lead  of  an  engine? 

A. — The  amount  of  steam  port  opening  just 
before  the  end  (or:  at  the  very  beginning)  of 
either  stroke  of  the  piston. 

Q. — How  would  you  give  lead  to  a  valve? 

A. — By  moving  the  eccentric  in  the  direction 
that  the  engine  is  to  run.  (See  page  100.) 

Q. — How  would  you  alter  a  valve  to  cut  the 
steam  off  at  a  given  part  of  the  stroke? 

A. — As  the  case  demands  add  lap  to  or  take  off 
from  the  steam  edge  of  valve. 

Q._What  is  lap? 

A. — The  distance  that  the  valve  laps  over  the 
steam-points,  when  in  mid-position. 


THE    ENGINE  103 

Q. — Is  there  any  lap  on  the  exhaust  edges  of 
valve? 

A. — Yes.  They  serve  to  delay  and  shorten  the 
exhaust  and  thus  to  increase  compression. 

Q. — Have  all  engines  exhaust  lap?* 

A. — Practically  yes,  and  they  have  the  more 
lap,  the  shorter  and  quicker  their  travel. 

Q.  — Why  is  lap  given  to  a  steam  valve? 

A. — So  the  port  will  close  before  the  piston 
reaches  the  end  of  the  stroke  and  make  the  steam 
io  work  by  its  own  expansion. 

Q. — What  is  meant  by  "%  cut-off"? 

A. — In  an  engine  with  a  24"  piston  stroke  it 
would  mean  that  the  steam  port  is  closed  when  the 
piston  has  traveled  6  inches,  or  the  first  quarter 
of  its  stroke. 

Q. — How  many  expansions  are  there  in  our  case? 

A. — At  the  quarter  stroke,  one  expansion ;  at  the 
half  stroke,  two  expansions ;  at  the  three  quarter 
stroke,  three ;  and  at  the  full  stroke,  four. 

Q. — How  do  you  decide  the  proper  amount  of 
steam  lap  on  a  slide  valve? 

A. — The  length  of  the  piston  stroke,  minus  the 
part  of  stroke  before  the  cut-off,  is  divided  by  the 
whole  length ;  extract  square  root  of  the  quotient. 
Multiply  this  square  root  by  one-half  the  length 
of  the  stroke  of  the  valve,  and  from  the  product 
take  one-half  the  lead  (if  any),  and  the  remainder 
will  be  the  amount  of  lap  required. 


104  QUESTIONS    AND    ANSWERS 

Example :  Given  a  48"  stroke,  travel  of  valve  6", 
to  cut  off  at  half  stroke,  no  lead.  Half  stroke 

2 

equals  24".  24-5-48  =  .50.  V~^T  =  .707. 
•  707  X  3  =  2. 121".  Ans.  (Sq.  root,  see  page  240. ) 

Q. — Should  the  lead  and  compression  in  the 
valve  of  a  vertical  engine  be  the  same  on  both 
ends  of  the  cylinder? 

A.  — No ;  the  lead  and  compression  at  the  lower 
end  of  the  cylinder  should  be  greater,  to  make  up 
(compensate)  for  the  weight  and  momentum  of 
the  piston,  crosshead  and  connecting  rod. 

Q. — What  is  the  difference  between  movable 
and  fixed  expansion? 

A.  — Movable  expansion  is  by  separate  gearing  or 
valves,  and  fixed  expansion  is  by  lap  of  slide  valve. 

Q. — Give  another  name  for  the  expansion  valve 
for  cut-off? 

A. — The  link  motion.     (See  page  144.) 


COMPOUND  ENGINES 

Q. — Explain  the  compound  engine? 

A. — A  compound  engine  is  one  that  has  two  or 
more  cylinders  following  in  regular  order  having 
increasing  diameters  so  arranged  that  the  exhaust 
steam  from  the  first  or  high  pressure  cylinder  is 
exhausted  into  the  second  or  larger  cylinder  to  do 
work  before  escaping  to  the  condenser. 


COMPOUND    ENGINES  105 

Q. — Explain  the  special  advantages  by  com- 
pounding? 

A. — First — Compounding  enables  the  fullest 
advantage  to  be  taken  of  the  expansive  power  of 
very  high  pressure  of  steam.  Second — The  ease 
with  which  it  may  be  adapted  to  work  on  one  or 
more  cranks,  thereby  reducing  the  excessive 
variation  of  strain  which  occurs  in  a  single  high 
pressure  engine. 

Q. — Classify  compound  engines? 
A. — First— Where  the  pistons  of  both  cylinders 
commence  the  stroke  at  the  same  time.     Second — 
Those  which  exhaust  from  one  cylinder  before  the 
next  cylinder  is  ready  to  receive  it,  in  which  case 
the  steam  is  retained  for  a  portion  of  the  stroke  in 
a  chamber  or  receiver  between  the  two  cylinders. 
Q. — What  kind  of  engines  would  you  call  them? 
A. — Receiver  engines. 

Q. — What  can  you  say  about  triple  and 
quadruple  expansion  engines? 

A. — The  principles  which  govern  the  compound 
are  the  same  in  the  triple  and  quadruple  expan- 
sion engines. 

Q. — What  is  a  cross  compound? 
A. — It  is  two  separate  engines  side  by  side  con- 
nected to  one  shaft,  one  being  a  high  pressure  and 
the  other  a  low  pressure.     (See  cut  page  10. ) 

Q.— What  is  meant  by  the  tandem  compound 
engine? 


io6 


QUESTIONS    AND    ANSWERS 


A. — It  is  where  the  high  and  low  pressure 
cylinders  and  engine  frame  are  one  behind  the 
other  (one  following  the  other). 

Q. — About  how  high  should  the  steam  pressure 
be  to  run  a  tandem  or  cross  compound  engine  with 
economy? 


NAMES  OF  PARTS  OF  TANDEM  COMPOUND  ENGINE 


1.  Crank  Pin. 

2.  Crank. 

3.  Crank  Shaft. 

4.  Main  Rod. 

5.  Governor  (fly  ball). 

6.  Valve  Chest  Covers 

7  Low  Pressure  Cylinder. 

8  High  Pressure  Cylinder. 
9.  Globe  Valve. 

10.  Cylinder  Head. 

11.  High  Pressure  Exhaust 

Pipe. 


12.  Cross  Head. 

13.  Piston  Rod. 

14.  Engine  Frame. 
1R.  Main  Cap. 

16.  Low  Pressure  Exhaust. 

17.  Flywheel. 

18.  Guides. 

19.  Foundation  Bolts. 

20.  Engine  Foundation. 

21.  Bottom      Foundation 

Bolts. 


A. — The  boiler  pressure  should  be  from  no  to 
125  Ibs.  pressure  to  the  square  inch  to  work  well. 
For  triple  expansion  about  1 80  Ibs. ,  and  so  on  in 
proportion. 

Q. — Why  is  such  high  pressure  carried  for  com- 
pound or  triple  expansion  engines?  . 

A. — So  the  last  low  pressure  cylinder  will  be 


THE  CORLISS  ELECTRIC  ENGINE  STOP    107 

able  to  do  work  from  the  expansion  of  steam  that 
first  entered  the  high  pressure  cylinder. 

For  calculating  the  H.  P.  of  a  compound  engine, 
see  page  150. 


THE  CORLISS   ELECTRIC   ENGINE   STOP 

DESCRIPTION:  The  steam  valve  K  is  held  closed 
by  the  electro-magnet  O  and  armature  G,  as  long 
as  the  lever  H  is  in  upright  position.  When  the 
circuit  P  P  is  closed,  the  upper  end  of  lever  H  is 
released  and  steam  can  open  the  valve,  forcing  H 
into  the  position  indicated  by  dotted  lines.  The 
steam  is  thus  admitted  into  the  cylinder  A, 
closing  the  vertical  check  valve  J  and  forcing  the 
piston  C  upward.  The  end  of  the  piston  rod  C 
engages  the  clamp  D,  attached  to  the  side  rod  M, 
raising  the  governor  balls  N  N  to  their  highest 
position.  Then  check  valve  L  closes,  holding  the 
governor  balls  in  their  highest  position.  Thus  the 
grab  hooks  are  prevented  from  opening  the  main 
valve. 

The  electric  circuit  P  P  is  closed  at  will  by 
pressing  a  button  conveniently  located,  or  it  may 
be  closed  automatically  at  any  desired  limit  of 
speed  by  means  of  the  SPEED  LIMIT  STOP  ATTACH- 
MENT, 

This  device  consists  of  two  adjustable  points  F 
F,  electrically  connected  and  so  placed  that  the 


108 


COMPRESSION    ENGINE  109 

clamp  D  is  brought  in  contact  with  one  of  them 
at  the  highest,  and  with  the  other  at  the  lowest, 
desired  limit  of  speed.  This  contact  closes  the 
circuit,  the  lever  H  is  released,  etc.,  as  above 
described. 

To  put  the  engine  stop  in  working  order  again, 
the  lever  H  is  replaced  in  the  upright  position, 
the  drip  valve  I  is  opened  to  allow  the  governor 
balls  to  resume  their  normal  position,  and  the 
valves  are  set  in  the  proper  position  by  rocking 
the  wrist  plate  backward  and  forward. 


THE  HOT  AIR  PUMPING  ENGINE 

(See  Sectional  View  on  next  page  ) 
The  air  heated  in  F  expands,  driving  the  power 
piston  D  upward.  The  compression  piston  C 
moves  downward  at  the  same  time,  driving  the 
cold  air  through  H  into  F,  thus  increasing  the 
pressure  until  its  stroke  is  completed.  Then  the 
increased  pressure  forces  the  compression  piston 
C  up,  passing  back  from  F  to  C  through  .the 
regenerator  H,  where  the  heat  is  absorbed  by  the 
regenerator  plates.  By  this  cooling  the  pressure 
is  lowered  to  its  minimum,  the  power  piston 
descends  and  compression  begins  again.  The  air 
passing  from  C  to  F  through  H,  reabsorbs  heat 
from  the  regenerator  plates,  which  helps  to  aug- 
ment the  pressure  in  F.  (Pump,  see  page  88.) 


110         VIEW    OF    COMPRESSION    ENGINE 


DESCRIPTION 


A  —Compression  Cylinder. 

B.— Power  Cylinder. 

C.— Compression  Piston. 

D. — Power  Piston. 

K.— Cooler. 

F.— Heater. 

G. — Telescope. 

H.— -Regenerator. 

II.— Cranks. 

JJ.— Connecting  Rods. 

KK.— Piston  Packings, 
(leather.) 

L,.—  C  heck 
Valve,  plac- 
ed at  back 
of  compres- 
sion cylin- 
d  e  r.  but 
shown  at 
side  on  cut. 


M.— Pump  Primer. 
N.— Blow-off  Cock. 
OO.— Knuckles. 
PP.— Heater  Bolts. 
R.— R'g'n'r't'r  Bon'et. 
SS.— P'mp  V've  B'net. 
T.—  Water  •  Jacket,    to 

protect   packing 

From  heat. 

UU.— Pump  Buckets. 
V.— Pump  Gland. 


OILING    DEVICES 


III 


The  two  ends  of  each  connecting  rod  are  con- 
nected  by  a  tube  A,  in  which  is  fitted  a  rod  B, 
extending  from  the  upper  to  the  lower  brass,  and 
so  arranged  that  one  key,  E,  at  once  takes  up  the 
lost  motion  on  both  brasses  C,  D.  The  key  is 
nicely  adjusted  by  the  nuts  F,  G. 


The  pump  plunger  U  U  moves  up  and  down 
with  the  compression  piston  C,  to  the  top  of 
which  the  plunger  rod  is  connected. 

SIGHT    FEED   AND     OILING     DEVICES    FOR   ENGINE    AND 
MACHINERY  BEARINGS 


Cross  Drip  Valve, 


Straight  Drip  Valve.      Angle  Drip  Valve,       Cross^Sight-Feed 


Straight  Stght-Fee4 
Valve* 


112 


QUESTIONS    AND    ANSWERS 


A. — Regulating  valve. 

B  —  One  of  the  flat  places  to 

hold  spring  C, 
D.— Packing  nut. 
.— Light  glass. 


Plain-Wiper  Cup.  -UbfizOr/kl  Wick  Wiper    Oil  Cup  Wiper 
•Cup. 


Drip  Trough. 


CONDENSERS 

Q.— What  is  a  condenser  as  applied  to  an  engine? 

A. — It  is  a  part  of  the  low  pressure  engine  and 
is  a  receptacle  into  which  the  exhaust  enters  and 
is  there  condensed. 


CONDENSERS  113 

Q. — What  are  the  principles  which  distinguish  a 
high  from  a  low  pressure  engine? 

A. — The  high  pressure  is  over  40  Ibs.  and  ex- 
hausts into  the  atmosphere,  while  the  low  pressure 
is  below  40  Ibs.  and  exhausts  into  the  -condenser. 

Q. — What  is  the  object  of  a  condenser  as 
applied  to  an  engine? 

A.  — It  saves  a  large  mass  of  pure  hot  water  for 
the  boiler,  and  it  maintains  a  constant  vacuum  in 
front  of  the  piston. 

Q. — Does  this  vacuum  aid  the  steam  in  moving 
the  piston? 

A. — It  does,  to  the  amount  of  half  the  vacuum 
gauge  pressure. 

Q. — How  is  a  vacuum  maintained  in  a  con- 
denser for  a  compound  condenser  engine? 

A. — By  the  steam  used  being  constantly  con- 
densed by  the  cold  water  or  cold  tubes  and  the  air 
pump  continually  clearing  out  the  condenser. 

Q. — How  does  the  condensed  or  used  steam 
form  a  vacuum? 

A. — Because  a  cubic  foot  of  steam  at  atmos- 
pheric pressure  shrinks  into  about  i  cubic  inch  of 
water. 

Q.— What  is  a  surface  condenser? 

A. — It  is  a  chamber  or  receiver  for  the  exhaust 
steam,  through  which  pass  brass  tubes,  carrying 
the  cold  water  which  is  supplied  usually  by  a 
circulating  pump. 


114  QUESTIONS    AND    ANSWERS 

Q. — Why  is  it  called  a  surface  condenser? 
A. — Because  the  exhaust  steam  is  condensed  by 
the    surfaces    of    cold    water    tubes    and    then 
removed,   together  with  the   air   and  vapor,    by 
means  of  an  air  pump. 

Q. — Where  is  a  surface  condenser  most 
desirable? 

A.  — Where  condensed  steam  is  used  for  feeding 
boilers  and  distilled  water  is  used  for  making 
pure  ice. 

Q. — Explain  the  jet  condenser? 
A. — It  consists  of  a  chamber  in  which  the 
exhausted  steam  passes  through  a  spray  or  jet  of 
cold  water.  The  steam,  being  condensed,  falls 
with  the  injection  water  into  a  hot  well,  and  from 
there  it  is  pumped  out. 

Q.  — is  there  a  valve  between  the  pump  and  a 
jet  condenser?  If  so,  of  what  use  is  it,  and  what 
trouble  is  it  likely  to  give? 

A. — A  foot  valve  is  sometimes  placed  between 
the  pump  and  condenser.  Its  object  is  to  close  the 
condensing  chamber  on  the  down  stroke  of  the 
bucket  plunger  of  a  single  acting  pump,  allowing 
a  partial  vacuum  to  be  maintained  in  case  of  the 
failure  of  a  valve  on  the  bucket.  The  trouble 
likely  is  the  same  that  affects  other  water  valves 
under  the  same  conditions. 

Q.— Is  it  well  to  start  the  jet  condenser  together 
with  the  engine? 


CONDENSERS  115 

A. — It  should  be  started  before  the  engine 
begins  to  revolve,  and  it  must  be  started  very 
gradually. 

Q. — What  is  meant  by  a  vacuum? 

A. — A  space  void  of  matter. 

Q. — Can  a  perfect  vacuum  be  obtained? 

A. — No,  but  a  compound  condensing  engine 
exhausts  about  14 M  out  of  15  Ibs.  of  atm.  pressure 
(indicated  at  28^  inches  on  vacuum  gauge,  2 
inches  representing  one  pound). 

Q. — Suppose  a  vacuum  gauge  indicates  26 
inches,  how  many  pounds  would  it  represent? 

A. — Thirteen  pounds. 

Q. — What  does  13  Ibs.  or  26  inches  vacuum 
signify  to  an  engineer  of  steam? 

A. — That  he  may  work  his  steam  down  to  4  Ibs. 
before  it  exhausts,  as  the  condenser  utilizes  13  of 
the  15  Ibs.  atmospheric  pressure.  Without  the 
condenser  the  engine  would  work  high  pressure. 

Q.— What  is  meant  by  the  term  "back  pressure"? 

A. — It  is  the  pressure  that  hinders  the  piston, 
equal  to  the  difference  between  a  perfect  vacuum 
and  what  the  gauge  reads. 

Q. — Is  it  possible  to  run  both  cylinders  of  a  com- 
pound engine  with  high  pressure? 

A.— It  is  a  very  rare  thing  to  feed  a  low-pressure 
cylinder  with  live  steam.  Few  of  them  would 
stand  a  high  pressure. 


THE    ECCENTRIC 

Q. — Explain  the  length,  throw  or  half  the 
stroke  of  engine  (crank)? 

A. — It  is  the  distance  between  the  center  of 
crank  pin  and  center  of  shaft. 

Q. — Explain  the  eccentric,  also  its  throw? 


A. — It  is  anything  out  of  center,  or  not  con- 
centric. It  serves  as  a  substitute  for  a  crank. 
The  throw  or  stroke  is  the  distance  between  the 
centers. 

Q. — Explain  what  is  understood  by  the  travel  of 
a  slide  valve? 

A. — It  is  twice  the  throw  of  the  eccentric. 

Q. — If  the  eccentric  was  made  a  half  inch 
larger  or  smaller  and  the  throw  left  the  same, 
would  it  affect  the  travel  of  the  valve? 

A. — No;  it  only  affects  the  straps. 

Q.— Why  not? 

116 


THE    ECCENTRIC 


117 


UPPER  PIN. 


LOWER  PIN. 


SHAFT. 


A. — Because  the  throw  or  stroke  is  the  only 
point  that  regulates  the  travel  of  valve. 

Q. — Explain  the  meaning 
of  direct  and  indirect  valve 
motion? 

A. — When  the  two  con- 
nections are  on  the  same 
side  of  the  rock  shaft,  they 
move  in  the  same  sense 
(direct).  When  they  are  on 
opposite  sides  of  the  rock  shaft,  they  move  in 
opposite  senses  (compound  or  indirect). 

Q. — Can  you  set  a  slipped  eccentric  without 
moving  steam  chest  cover,  and  how? 

A. — Yes.  Open  cylinder  cocks,  roll  crank  pin 
over  in  the  direction  engine  runs  till  the  pin  is  on 
"dead  center,"  then  open  throttle  slightly.  Roll 
the  eccentric  forward  in  the  direction  the  engine 
runs  until  steam  escapes  from  cylinder  cock  at  the 
end  where  the  valve  should  begin  to  open,  screw 
the  eccentric  fast  to  the  shaft,  roll  the  crank  over 
to  the  other  "dead  center"  and  see  if  steam 
escapes  at  the  opposite  end  of  cylinder ;  if  so  the 
engine  is  ready  to  run  until  an  opportunity  occurs 
to  open  the  valve  chest  and  examine  the  valve  and 
set  properly. 


DEAD  CENTER 

A  simple  way  of  finding  the  exact  "dead  center" 
of  an  engine  is  as  follows: 

.Place  a  stationary  rest  close  to  the  rim's  edge  of 
the  fly  wheel  or  crank  disc,  at  the  side  furthest 
away  from  the  crosshead ;  roll  the  crank  pin  over, 
until  the  crosshead  is  within  one-half  inch  of  the 
end  of  its  travel  in  one  direction ;  make  a  well- 
defined  mark  on  the  guide  at  the  end  of  the  cross- 
head  ;  then  lay  a  square  across  the  stationary  rest 
and  with  chalk  and  a  scriber  mark  the  rim's  edge 
of  the  fly  wheel  or  disc. 

Then  roll  the  crank  pin  in  the  same  direction 
past  the  center  until  the  same  end  of  the  crosshead 
comes  to  the  same  mark  on  the  guide,  then  lay  a 
square  on  the  stationary  rest  and  scribe  another 
line  on  the  rim's  edge  of  fly  wheel  or  disc. 

Then  take  a  pair  of  dividers  and  find  the  middle 
between  the  two  points  just  marked.  This  middle 
point  will  correspond  exactly  with  the  "dead 
center"  of  the  engine.  Mark  the  point  with  a 
center  punch. 

Then  roll  the  engine  over,  until  the  crosshead 
comes  to  the  opposite  end  of  the  slides,  and  pro- 
ceed as  before  to  find  the  "dead  center"  at  the 
other  end  of  the  stroke. 

118 


ENGINE    POUNDING  IIQ 

Another  way  is  by  the  use  of  an  adjustable 
spirit  level.  The  level  is  adjusted  to  the  guides 
and  then  the  crank  pin  strap  is  adjusted  to  that 
level. 


ENGINE  POUNDING 

Q.  — Can  you  describe  the  common  causes  of  an 
engine  pounding? 

A.— Yes. 

Q.— Name  them? 

A. — Crank  pin  not  being  square  (at  right 
angles,  L)  with  the  crank,  caused  by  faulty  work- 
manship, an  engine  being  out  of  square,  lost  motion 
in  crank,  in  crosshead  pin  or  journal  boxes,  leaky 
piston  rings,  unbalanced  valve,  crank  disc  and 
pulley  wheels,  valve  not  being  properly  set,  poor 
lubrication,  loose  piston-head,  water  in  cylinder, 
and  many  others. 

Q. — Can  you  tell  whether  a  crank  pin  is  out  of 
square? 

A.— Yes. 

Q. — In  what  way? 

A.  — The  slightest  variation  can  be  found  by  a 
good  spirit  level,  which  is  used  as  follows:  First, 
disconnect  the  main  rod  from  the  crosshead,  then 
key  the  rod  to  the  crank  pin  so  the  rod  can  turn 
without  moving  sidewise ;  then  place  the  rod  in  a 
position  to  move  easily  as  the  crank  is  turned. 


120  QUESTIONS    AND    ANSWERS 

Fasten  a  spirit  level  to  the  rod  with  a  clamp  in  line 
with  the  shaft  (right  angles  with  rod).  When  the 
crank  is  turned  the  bulb  in  level  should  not 
change.  If  it  does  the  pin  is  not  square  with  disc 
nor  parallel  with  shaft. 

Q. — Does  it  make  any  difference  if  the  shaft  is 
not  level  when  testing  crank  pin? 

A.— No;  the  point  that  the  bulb  in  the  spirit 
level  moves  to,  when  clamped  to  the  rod,  is  the 
point  where  it  should  stay  the  full  revolution. 

Q. — If  the  crank  pin  is  not  properly  set,  how  will 
the  bulb  show? 

A. — It  would  move,  and  the  more  the  pin  is  out 
of  square,  the  more  the  bulb  will  move. 


LINING,  LEVELING   AND   SQUARING  AN 
ENGINE  SHAFT 

Q. — Name  handy  tools  for  lining  engines  and 
taking  measurements? 

A.  -Spirit  level,  light  chalk  line,  calipers,  rule, 
square,  slotted  piece  of  wood  for  end  of  cylinder  to 
hold  line,  and  a  tram. 

Q. — How  would  you  line  an  engine,  also  square 
and  level  a  shaft? 

A. — First,  disconnect  and  remove  all  parts  from 
crank  pin  to  back  cylinder  head,  then  bolt  a  slotted 
stick  to  farthest  end  of  cylinder  from  crank  pin,  to 


LINING,    LEVELING    AND    SQUARING     121 

which  attach  a  string  and  pass  it  over  the  point, 
thence  through  the  cylinder  to  end  of  bed  plate 
and  fasten  so  it  can  be  adjusted  to  the  center. 


Q. — How  is  the  adjusting  done? 

A. — With  inside  calipers. 

Q.  — From  where  do  you  line? 

A. — From  the  two  counter-bores. 

Q. — Why  center  from  counter-bores  and  not 
from  the  regular  bore  of  the  cylinder? 

A. — Because  they  are  not  worn,  while  the 
regular  bore  is. 

Q. — How  would  you  square  the  shaft  of  an 
engine? 

A.  — Move  the  crank  pin  both  ways,  forward  and 
back,  above  the  center  line  of  cylinder.  If  the 
center  line  intersects  the  crank  pin  both  times  at 
the  same  point,  then  the  latter  is  square  with  the 
cylinder.  If  not,  shift  the  outbearing  of  shaft. 

Q. — How  would  you  level  the  shaft? 

A.  — Drop  a  plumb  line  below  and  near  center 
line  and  in  front  of  the  center  of  shaft,  then  try 


.122 


QUESTIONS    AND    ANSWERS 


the  pin  at  top  and  bottom — half  strokes — same  ai 
in  squaring. 

Q. — How  would  you  know  if  shaft  was  in  line 
with  center  of  cylinder  or  proper  height? 

A. — By  placing  square  against  disc  (or  crank) 
face  and  bringing  up  to  line. 

Q. — Howlis  the  proper  length  of  main  rod  found, 


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S!HAFT  LINE 

also  the  clearance  between  the  piston  and  cylinder 
head  when  engine  is  at  either  dead  center? 

A. — By  first  finding  the  striking  points,  pushing 
the  piston  to  one  end  of  cylinder,  then  to  the 
other,  marking  the  crosshead  and  guide.  After 
this  is  done  find  the  full  stroke  of  engine  by 
measuring  from  center  of  shaft  to  center  of  crank 
pin.  The  distance  found  is  one-half  of  stroke. 
The  difference  between  full  stroke  and  the  tw# 


LINING,    LEVELING   AND   SQUARING     123 

striking  points  is  full  clearance  for  both  ends. 
After  this  is  known  move  the  crosshead  (with 
piston  attached)  back  from  striking  point  one-half 
of  full  clearance,  which  will  give  an  equal 
clearance  for  both  ends,  viz. :  Distance  between 
striking  points  is  17%  inches,  stroke  of  engine  16 
inches,  full  clearance  i%  inches;  the  half  will  be 
3^  inch  clearance  at  each  end  of  cylinder.  Then 
place  the  crank  pin  on  same  dead  center  at  which 
the  crosshead  is  placed  and  measure  the  length  of 
rod  with  a  tram  from  center  of  crank  pin  to  center 
of  crosshead  (wrist)  pin. 

Q. — How  are  the  guides  put  in  line? 

A. — For  level,  lay  a  straight  edge  across  the  two 
guides  and  caliper  between  it  and  the  center  line 
the  whole  length  of  the  guides.  For  proper 
alignment  across,  caliper  between  the  guide  edges 
and  the  center  line  the  whole  length. 

Q. — What  do  you  do,  after  the  guides  are 
properly  lined? 

A.  — Remove  the  line.  Place  the  piston  in  the 
cylinder  and  place  the  crosshead  on  the  piston, 
keying  it  on,  or  screwing  it  on  as  the  case  may  be. 
Then  line  the  piston  rod  by  the  guides  for  level 
and  sideways  at  both  ends  of  guides. 

Q. — What  do  you  do  when  the  cylinder  is  worn 
so  that  the  piston  center  is  out  of  line. 

A. — Put  shims  of  tin  under  the  spider  between 
the  lugs  and  bull  ring,  until  the  piston  center  is 


124         AUTOMATIC    SHAFT    GOVERNOR 

central,  then  adjust  the  packing  rings  by  the 
setting  out  or  tension  springs. 

Q. — How  do  you  line  the  crank  pin  with 
cylinder? 

A. — Place  the  connecting  rod  on  the  crank  pin, 
and  key  up  the  brasses  until  they  hug  the  crank 
pin  snugly.  Then  move  the  crank  pin  to  one  of 
the  dead  points,  and  measure  with  inside  calipers 
how  far  the  side  of  the  brasses  on  the  opposite  end 
of  the  rod  is  from  the  guide.  Then  move  the 
crank  to  the  other  dead  center  and  measure  the 
distance  on  the  other  end  of  the  guide.  If  these 
two  distances  are  the  same,  the  crank  pin  is  per- 
fectly in  line. 

AUTOMATIC  SHAFT  GOVERNOR  FOR 
SIDE  CRANK  ENGINE 

DESCRIPTION:  In  following  cut,  A  indicates  the 
hole  in  the  tripod  (a  seat  or  instrument  with  three 
feet  or  arms)  B,  through  which  the  engine  shaft 
passes.  The  eccentric  C  is  hung  to  the  long  arm 
of  the  tripod  B  by  a  stud  and  secured  by  a  screw 
with  washer.  The  hole  through  the  eccentric  is 
much  larger  than  the  shaft,  which  permits  the 
center  of  the  eccentric  to  shift  across  the  shaft, 
thus  varying  its  throw.  The  eccentric  is  supported 
and  guided  by  a  gibbed  rebate  fitting  over  a  project- 
ing lip  on  the  tripod.  The  dead  wheel  D  is  fitted 
loosely  on  the  hub  of  the  tripod  so  that  it  may 


FOR    SIDE    CRANK    ENGINE  125 

remain  stationary  while  the  tripod  turns  within  it. 
The  weights  E,  E  are  pivoted  to  the  dead  wheel 
by  pins,  fastened  with  set  screws,  and  are  con- 
nected with  studs  to  the  short  arms  of  the  tripod 


by  the  weight  links  F,  F.  The  springs  G,  G  are 
pivoted  to  the  weights  by  their  rods,  and  rest 
upon  lugs  on  the  arms  of  the  dead  wheel.  They 
are  precisely  alike,  acting  together  as  one.  .  The 
weights  and  weight  links,  as  well  as  the  springs, 
are  duplicated  only  to  secure  more  perfect  balance 
of  the  governor.  The  eccentric  link  H  connects 
the  eccentric  with  the  rim  of  the  dead  wheel  by 
pins,  which  are  made  tapering  to  provide  means 
for  taking  up  the  wear.  O,  O,  O,  O,  O  represent 
oil  holes  in  dead  wheel. 


126          AUTOMATIC    SHAFT    GOVERNOR 

To  SET  THE  VALVE:  The  governor  should  set 
on  the  shaft  so  that  the  center  of  the  long  arm  of 
the  tripod,  to  which  the  eccentric  arm  is  attached, 
is  on  the  other  side  of  the  main  shaft,  directly 
opposite  the  crank  pin,  and  keyed  in  that  position. 

The  steam  valve  that  the  governor  controls 
should  be  adjusted  to  uncover  the  ports  an  equal 
distance  on  each  end  and  should  be  set  (while 
the  weights  are  blocked  out)  as  close  to  the  rim  of 
the  dead  wheel  as  the  set-screw  in  the  outer  side 
of  one  of  the  weights  will  allow  them  to  go. 

Place  the  engine  crank  pin  on  the  inner  dead 
center  and  allow  the  valve  to  just  cover  the  steam 
port  at  the  outer  end  of  the  cylinder ;  that  is,  the 
outer  end  (edge)  of  the  valve  being  line  and  line 
with  the  outside  edge  of  the  outer  port.  Turn  the 
crank  pin  (or  engine)  in  the  direction  it  is  to  run 
(over  or  under)  to  the  outer  center,  and  the  inner 
end  of  the  valve  should  correspond  in  like  manner 
with  the  outside  edge  of  the  inner  port.  If  it  does 
not,  equalize  the  difference  by  the  nuts  on  the 
valve  rod. 

Roll  the  engine  to  the  inner  center  again  to  be 
certain  that  the  adjustment  is  right,  and  when 
this  is  accomplished  the  valve  is  correctly  set. 

The  governor  should  be  so  placed  on  the  shaft 
that  the  eccentric  is  exactly  in  line  with  the  valve 
crosshead  pin  and  does  not  touch  the  side  of  the 
main  shaft  bearing. 


FOR    SIDE    CRANK    ENGINE  127 

MANAGEMENT  AND  CARE:  All  movements  from 
the  steam  valve  to  the  governor  parts  should  be 
free,  smooth,  and  without  lost  motion.  To  have 
the  governor  in  order  keep  it  clean  and  all  pins 
and  bearings  well  oiled. 

The  cut  shows  five  oil  holes  through  the  rim  of 
the  dead  wheel,  marked  O.  There  are  also  two 
in  the  hub.  These  are  closed  with  plugs  which 
are  removed  when  oiling.  Use  good  oil  and  oil 
frequently.  Should  the  governor  work  irregularly 
or  fail  to  control  the  engine  the  cause  will  usually 
be  found  in  some  dry  joint  or  place  that  binds. 

When  there  is  a  set  screw  on  the  inner  side  of 
the  weight  it  is  to  limit  the  travel  toward  the  hub, 
and  should  never  be  removed  or  disturbed.  The 
».  governor  key  should  fit  closely  on  the  sides  of  the 
key  way,  but  never  on  the  top  and  bottom,  to  avoid 
springing  the  tripod  hub  and  causing  the  dead 
wheel  to  bind. 

If  governor  should  become  gummed  from  bad 
oil,  take  out  springs,  first  carefully  measuring 
their  length  in  position.  This  precaution  is 
necessary  so  they  may  be  replaced  exactly  in  the 
same  position.  Take  out  one  at  a  time  to  avoid 
disarrangement.  Clean  with  kerosene,  etc.  Before 
tension  is  again  put  on  the  springs,  move  the  dead 
wheel  back  and  forth  to  see  that  there  is  no  bind- 
ing in  any  of  the  working  parts. 

To  CHANGE  SPEED  by  changing  the  tension  of 


128          AUTOMATIC    SHAFT    GOVERNOR 

the  springs:  To  run  faster,  tighten;  to  run 
slower,  loosen.  Or  move  the  weights.  Never 
tighten  the  springs  down  so  that  their  spirals 
touch  each  other.  Never  tighten  or  loosen  the 
spring  more  than  one  inch  beyond  its  set  tension. 
If  greater  speed  be  desired  than  can  be  obtained 
from  the  springs  and  weights  furnished  with  the 
governor,  others  should  be  ordered  from  engine 
builder.  Be  sure  to  mention  speed  desired. 

REVERSING  governor  and  engine  to  run  over 
or  under:  Remove  the  set-screw  from  the  outer 
side  of  the  weight.  Disconnect  the  eccentric  link 
H  from  the  eccentric  and  from  the  rim  of  the  dead 
wheel  by  removing  the  pins  from  the  lugs  b  and 
d.  Take  hold  of  the  rim  of  the  dead  wheel  with 
a  monkey-wrench  and  pull  it  around  on  the  shaft  . 
as  far  as  it  will  go,  in  the  direction  the  engine  is 
to  run,  and  again  connect  the  eccentric  with  the 
rim  of  the  dead  wheel  by  inserting  the  eccentric 
link  H  into  the  other  pair  of  lugs  marked  b.  and 
d,  using  care  in  replacing  the  pins  not  to  drive 
them  so  tight  as  to  bind.  Replace  the  set-screw 
in  the  outer  side  of  the  weight  in  exactly  the  same 
position  as  before.  This  reverses  the  governor 
and  the  engine  is  ready  for  service. 


HOW   TO   KNOW   STEEL   FROM   IRON 

A  drop  of  aqua  fortis  turns  steel  brown,  and 
cast-iron  black,  while  (wrought)  iron  is  not 
affected. 


AUTOMATIC  GOVERNOR  FOR  SELF- 
CONTAINED  ENGINES 

SUCH     AS    DOUBLE     CRANK    DISC     AND     TWO     PULLEY 
WHEELS,    ONE   EACH   SIDE  OF   CRANK  PIN 

DESCRIPTION:  In  the  following  cut,  B  is  the 
eccentric,  hung  on  the  hub  M  of  the  band  wheel 
by  a  pin,  which  is  made  tapering  to  provide  means 
for  taking  up  the  wear.  The  hole  through  the 
eccentric  is  much  larger  than  the  shaft  and  per- 
mits the  center  of  the  eccentric  to  shift  across  the 
shaft,  thus  varying  its  throw.  Piece  C  is  the 
eccentric  arm,  which  transmits  the  shift  motion  to 
the  eccentric  through  the  steel  bands,  or  ribbons, 
which  are  fastened  by  clamps  to  the  eccentric 
arms  and  by  screws  to  the  eccentric.  The  arm  is 
securely  fastened  to  a  rocker  shaft,  which  passes 
through  one  of  the  arms  of  the  band  wheel,  and 
to  which  the  spring  crossheads  D,  D  are  also 
attached.  The  spring  crossheads  carry  the 
weight  bars  I,  I,  weights  G,  G,  and  the  spring 
rods  J,  J.  The  springs  K,  K  are  held  by  the 
spring  rods  and  are  precisely  alike,  acting  together 
as  one.  The  weights,  as  well  as  the  springs,  are 
duplicated  only  to  secure  more  perfect  balance  of 
the  governor. 

To  SET  THE  VALVE:  Governor  should  set  on 
129 


130 


AUTOMATIC    GOVERNOR 


the  shaft  so  that  the  center  of  the  rocker  shaft,  to 
which  the  eccentric  arm  C  is  attached,  is  on  the 
other  side  of  the  main  shaft,  directly  opposite  the 
crank  pin,  and  keyed  in  that  position.  The  steam 
valve  controlled  by  the  governor  should  be 


adjusted  to  uncover  the  ports  an  equal  distance  on 
each  end  and  should  be  set  while  the  weights  are 
out  as  far  as  the  stops  will  allow  them  to  go. 

Place  the  engine  on  the  "inner"  center  and 
allow  the  valve  to  just  cover  the  steam  port  at  the 
outer  end  of  the  cylinder  so  the  outer  end  of  the 
valve  will  be  line  and  line  with  the  outside  edge 


FOR   SELF-CONTAINED    ENGINES         131 

of  the  outer  port.  Turn  the  crank  pin  in  the  direc- 
tion it  is  to  run  to  the  "outer"  center,  and  the 
inner  end  of  the  valve  should  correspond  in  like 
manner  with  the  outside  edge  of  the'inner  port. 
If  it  does  not,  equalize  the  difference  by  the  nuts 
on  the  valve  rod. 

Roll  the  engine  forward  again  to  the  "inner" 
center  to  be  sure  that  the  adjustment  is  right,  and 
when  this  is  accomplished  the  valve  is  set. 

MANAGEMENT  AND  CARE  should  be  the  same  as 
for  side  crank  engine  governor. 

To  CHANGE  SPEED:  Same  as  for  side  crank 
engine  governor.  The  speed  may  also  be  changed 
by  altering  the  positions  of  the  weights  on  the 
bars.  Sliding  them  toward  the  spring  crossheads 
increases  the  speed,  and  in  the  opposite  direction 
decreases  it. 

Should  a  greater  speed  be  desired  than  can  be 
obtained  from  the  springs  and  weights  furnished 
with  the  governor,  see  instructions  for  speed 
changing  on  side  crank  engine  governor. 

To  REVERSE  governor  for  running  over  or  under: 
Remove  the  eccentric  strap,  then  take  out  the  key 
from  the  governor  band  wheel,  slip  the  wheel  out 
to  the  end  of  the  shaft,  remove  the  taper  pin  on 
which  the  eccentric  swings,  move  the  eccentric  to 
the  other  hole  in  the  hub,  replace  the  taper  pin  in 
the  eccentric,  using  care  that  it  is  not  screwed  in 
so  tight  as  to  bind,  change  the  weight  bars  to  the 


132  AUTOMATIC    GOVERNOR 

other  ends  of  the  spring  crossheads,  reversing  their 
positions,  loosen  the  nuts  that  hold  the  tension  on 
the  springs,  being  careful  to  measure  the  springs 
before  removing  the  nuts,  so  as  to  replace  them  in 
exactly  the  same  positions. 

After  the  springs  are  free  from  tension  take  out 
the  small  split  pins  that  hold  the  ends  of  the 
spring  rods  in  their  places,  remove  both  spring 
rods  and  turn  them  end  for  end,  then  replace  the 
split  pins. 

Before  tension  is  again  put  on  the  springs,  move 
the  weight  bars  back  and  forth  to  see  that  there  is 
no  binding  in  any  of  the  working  parts.  Also  see 
that  the  eccentric  travels  its  entire  throw  across 
the  shaft,  and  that  both  of  the  lips  strike  the  top 
plate  that  is  bolted  to  the  face  of  the  wheel  hub, 
back  of  the  eccentric.  Should  the  eccentric  strike 
on  one  point  and  not  on  the  other,  loosen  the 
clamps  that  hold  the  steel  bands,  or  ribbons,  move 
the  eccentric  just  far  enough  to  enable  both  points 
to  touch,  then  refasten  the  clamps. 

Should  the  set-screws  under  the  spring  crosshead 
strike  before  the  eccentric  touches  the  stop,  adjust 
them  accordingly. 

Place  the  required  tension  on  the  springs,  slip 
the  wheel  back  to  its  place,  drive  in  the  key, 
replace  the  eccentric  strap  and  the  engine  is  ready 
to  start. 


BALANCED  SLIDE  VALVE 

Q._What  do  the  following  cuts  represent? 

A.— The  balanced  slide  valve  of  an  automatic 
self-contained  engine,  protected  from  steam 
pressure  by  a  hood. 


Q._ What  does  the  first  cut  represent? 

A. — It  is  the  valve  and  seat  with  hood  detached. 


Q.—What  does  the  second  cut  represent? 
A.— A  section  through  the  valve  and  hood  on  the 
line  A  B,  shown  in  the  next  cut. 
133 


134  QUESTIONS    AND    ANSWERS 

Q. — What  does  the  third  cut  represent? 
A. — It   is  a  perspective  view  of  the  valve  and 
hood  complete. 


B 


Q. — How  is  the  balancing  of  valve  accomplished? 

A. — The  exposed  ends  of  valves,  being  of  equal 
area,  balance  each  other. 

Q. — How  is  the  pressure  counterbalanced? 

A. — By  recesses  of  equal  area  with  the  ports 
under  the  hood  and  over  the  valve. 

Q. — What  friction  is  there  to  overcome? 

A. — The  only  friction  is  the  weight  of  a  very 
light  valve. 

Q. — How  is  a  worn  valve  refitted? 

A. — By  scraping. 

Q. — What  is  provided  for  the  case  of  excessive 
pressure  or  water  in  the  cylinder? 

A. — The  hood  is  set  loose  on  the  seat,  and  readily 
yields. 

Q. — What  guides  the  hood  to  its  correct  seat? 

A. — The  springs  and  studs. 

Q. — What  is  the  port  action,,  of  the  valve? 

A. — It  is  that  of  any  plain  slide  valve. 

Q. — What  quickens  the  opening  and  closing  ot 
the  ports? 


CORLISS    ENGINE 


135 


A. — The  recesses  in  the  hood  over  the  valve. 
Q. — What  advantage  has  this  valve? 
A. — All  the  advantages  of  a  perfectly  balanced 
slide  valve. 


CORLISS  ENGINE 

The  Corliss  valve  gear  is  a  detachable  gear. 
There  are  four  valves — two  steam  valves  and  two 
exhaust  valves  all  connected  to  one  center  wrist 
plate.  The  wrist  plate  pin  is  connected  to  rocker 
arm  by  reach  rod,  and  from  there  to  eccentric  by 
another  rod. 


1.  Fly  ball  gov. 

2.  Gag  pot. 

3.  Gov.  stand. 
3A.  Bevel  gear 

case. 

4.4.  Gov.   rods. 

5.5.  Steam 

valves. 


6,6.  Exhaust  valves. 
7.  Wrist  and  rocker  con- 
necting rod. 
,  8.  Dash  pots  and  rods. 
9.  Eccentric  rod. 

10.  Governor    belt    and 

pulleys. 

11.  Eccentric  and  strap. 


12.  Rocker  arm. 

13.  Wrist  plate. 

14.  Cylinder  Bracket. 

15. 15.  Steam  valve  (adjust- 
ing) rods. 

16. 16.  Exhaust  valve  rods. 

TYPICAL    CORLISS   VALVE    GEAR 

To  SET  VALVES,  tal^e  off  the  back  caps  or  back 
heads  of  all  four  valve  chambers.  Guide  lines 
will  be  found  on  the  ends  of  the  valves  and 
chambers,  as  follows:  On  the  steam  valves,  lines 


136 


CORLISS    ENGINE 


indicating  the  working  edges  of  the  steam  ports; 
on  the  exhaust  valves  and  ports,  guide  lines  for 

CORLISS  VALVE  OPENING  OUT 


the  purpose  of  setting  them.  As  stated  before,  the 
wrist  plate  is  centrally  located  between  the  four 
valve  chambers  on  the  valve  gear  side  of  the 

STEAM    ,    WAY. 


cylinder.      A  well-defined  line  will  be  found  on 
the  bracket  which  is  bolted  to  the  cylinder,  and 


CORLISS    ENGINE 


137 


three  lines  on  the  hub  of  wrist  plate,  which,  when 
they  correspond  with  the  single  line  on  the 
bracket,  show  central  position  of  the  wrist  plate, 
and  the  extremes  of  its  throw  or  travel  both  ways. 

To  ADJUST  THE  VALVC  first  unhook  the  reach 
or  carrier  rod  connecting  the  wrist  plate  with 
rocker  arm,  then  hold  the  wrist  plate  in  its  central 
position. 

The  connecting  rods  between  steam  and 
exhaust  valves  and  wrist  plate  are  made  with  right' 
and  left  hand  screw  threads  on  their  opposite  ends, 
and  provided  with  jamb  nuts,  so  that  by  slacking 


the  jamb  nuts  and  turning  the  rods  they  can  be 
lengthened  or  shortened  as  desired.  By  means  of 
this  adjustment  set  the  steam  valves  so  that  they 
will  have  %  inch  lap  for  10  inch  diameter  of 


138 


CORLISS    ENGINE 


cylinder,  and  y%  inch  lap  for  32  inch  diameter  of 
cylinder,  and  for  intermediate  diameters  in  pro- 
portion. 

FOR  THE  EXHAUST,  set  them  with  1-16  inch  lap 
for  10  inch  bore,  and  y&  inch  lap  for  32  inch  bore 
on  non-condensing  engines,  and  nearly  double  this 
amount  on  condensing  engines  for  good  results. 
Lap  on  the  steam  and  exhaust  valves  will  be 


CORLISS 

KNOCK-OFF  CAM  D  1 S  E  N  C  AC  I  N  G 
,NQ  STUD  CUT   OFF 

GEAR 

,TCH  SPRING 


shown  by  the  lines  on  the  valves  being  nearer 
the  center  of  the  cylinder  than  the  lines  on  the 
valve  chambers. 

Having  made  this  adjustment  of  valves,  the  rods 
connecting  the  steam  valve  arm  with  the  dash  pot 


CORLISS    ENGINE  139 

should  be  adjusted  by  turning  the  wrist  plate  to 
its  extremes  of  travel  and  adjusting  the  rod  of  each 
valve  so  that  when  it  is  down  as  far  as  it  will  go 
the  square  steel  block  or  stud  die  on  the  valve 
arm  will  just  clear  the  latch  die  on  the'latch  hook. 

If  the  rod  is  left  too  long  the  steam  valve  stem 
would  likely  be  bent  or  broken ;  if  too  short,  the 
hook  will  not  engage,  and,  consequently,  the  valve 
will  not  open. 

Having  adjusted  the  valves  as  stated,  hook  the 
engine  in,  and,  with  the  eccentric  loose  on  shaft, 
turn  it  over  and  adjust  the  eccentric  rod  so  that 
the  wrist  plate  will  have  the  correct  extremes  of 
travel,  as  marked  on  the  wrist  plate  hub. 

If  marks  on  wrist  plate  do  not  agree  at  each  full 
throw  with  bracket  marks,  disconnect  strap  from 
eccentric  rod  and  adjust  the  screw  on  stub  end,  as 
required,  until  marks  do  agree,  both  forward  and 
backward;  then  place  the  crank  on  dead, center 
and  turn  the  eccentric  in  direction  engine  is  to 
run,  until  an  opening  of  1-32  or  1-16  is  shown  at 
steam  valve,  then  throw  crank  pin  on  other  (lead 
center  to  secure  the  desired  lead  in  opposite 
motion.  If  lead  is  not  the  same,  adjust  by 
lengthening  or  shortening  the  connecting  rods 
between  the  eccentric  and  wrist  plate  as  the  case 
may  be. 

To  ADJUST  THE  RODS  connecting  the  cut-off  or 
tripping  cams  with  the  governor,  have  the  gov- 


140 


CORLISS    ENGINE 


ernor  at  rest  and  the  wrist  plate  at  one  extreme 
of  its  travel.  Then  adjust  the  rod  connecting 
with  the  cut-off  cam  on  the  opposite  steam  valve, 


CORLISS 


VACUUM 


ENGINE 


DASH  POT. 


LEATHER 

'ACKiNQ 


so  that  the  cam  will  clear  the  steel  or  latch  die  on 
the  tail  of  the  hook  about  1-32  of  an  inch.  Turn 
the  wrist  plate  to  the  opposite  extreme  of  travel 
and  adjust  the  cams  for  the  other  valves  in  the 
same  manner. 


CORLISS   ENGINE  14! 

To  EQUALIZE  THE  CUT-OFF  and  test  its  correct- 
ness, hook  the  engine  in  and  block  the  governor 
up  about  halfway  in  the  slot,  which  will  bring  it 
to  its  average  position  when  running.  Then  turn 
the  disc  slowly  in  the  direction  which  it  is  to  run, 
and  note  the  distance  the  crosshead  has  traveled 
from  its  extreme  position  at  dead  center  when 
the  cut-off  cam  trips  or  detaches  the  steam  valve. 
Continue  to  turn  the  disc  beyond  the  other 
dead  center  and  note  the  distance  of  crosshead' s 
extreme  travel  when  valve  drops.  If  distance  is 
the  same  the  cut-off  is  equal ;  if  not,  adjust  either 
one  or  the  other  of  the  rods  until  the  distance  is 
the  same. 


Q. — Will  the  cut-off  mechanism  unhook  when 
governor  is  down? 

A. — No ;  it  keeps  the  valve  hooked  up  full  stroke. 

Q.— Will  the  latch  die  hook  on  stud  die  of  valve 
when  dash  pot  rod  is  too  short? 

A.— No. 

Q. — How  long  should  the  rod  be? 

A. — It  should  be  long  enough  so  when  the 
plunger  is  at  the  bottom  of  dash  pot  the  latch 
would  hook  over  the  latch  stud  (steel  block)  and 
the  stud  lie  clear  of  the  latch  (hook). 

Q. — What  prevents  the  dash  pot  rod  from  break- 
ing or  bending? 


142  QUESTIONS    AND    ANSWERS 

A. — The  cushion  of  the  plunger  on  air  in  the 
dash  pot. 

Q. — Have  the  plungers  any  packing  to  make 
them  close  fit? 

A. — Yes;  some  have  leather  packing,  others 
have  piston  rings. 

Q, — How  is  the  air  regulated  in  the  dash  pot? 

A. — By  means  of  an  air  valve  in  the  air  opening 
by  turning  a  screw  in  the  escape  hole. 

Q. — What  keeps  the  governor  in  regulation  so  it 
will  not  allow  the  engine  to  run  away  or  be  over- 
sensitive? 

A. — A  small  oil  reservoir  on  engine  frame  below 
governor,  known  as  the  gag  pot. 

Q. — What  kind  of  oil  is  generally  used  in  the 
gag  pot? 

A. — Kerosene  oil. 

Q. — How  would  you  give  the  governor  more 
freedom  of  motion? 

A. — By  removing  one  or  more  of  the  small 
screws  in  the  piston  plunger  of  gag  pot. 

Q. — How  would  you  warm  the  cylinder  of  a 
Corliss  engine  before  starting? 

A. — By  first  blowing  all  the  condensed  water 
out  of  the  steam  pipe  by  means  of  the  drip  valve 
provided  on  the  steam  valve  elbow  or  globe ;  then 
open  the  steam  valve  a  little  to  allow  the  valves 
and  cylinder  to  become  warm.  Unhook  rocker 
reach  rod,  and  work  valves  with  wrist  plate  by 


CORLISS    ENGINE  143 

nand  with  lever.  The  cylinder  soon  becomes 
warm  and  all  water  is  expelled  into  the  exhaust 
pipe,  the  exhaust  drain  cock  having  been  left 
open  to  allow  the  condensed  water  to  escape. 

Q. — Would  you  then  start  the  engine  up  lively? 

A. — No.  Let  engine  move  slowly  until  satisfied 
all  is  right,  then  open  throttle  gradually  until 
wide  open. 

Q. — Suppose  the  governor  belt  connection  broke, 
would  the  engine  run  away? 

A. — No;  the  trips  or  safeties  would  slip  in 
between  the  latches  and  dies  and  prevent  valves 
from  opening  or  latches  hooking  on  to  latch  dies. 

Q. — Suppose  the  governor  of  a  Corliss  engine 
would  allow  the  speed  to  fluctuate  from  one 
extreme  to  the  other,  where  would  you  look  for  the 
trouble? 

A. — The  oil  gag  pot  in  connection  with  the 
governor  will  very  probably  be  found  to  be 
empty,  on  inspection. 

Q. — In  the  majority  of  cases  where  the  governor 
gives  trouble,  what  would  you  lay  it  to?  » 

A. — Not  getting  proper  oiling,  being  dirty,  oil 
holes  plugged  and  not  good  enough  connection  to 
the  main  shaft. 

Q. — About  how  many  oil  holes  has  a  Corliss 
governor,  all  told? 

A. — From  10  to  13. 


LINK  MOTION  AND  VALVE   SETTING 


In  the  position  of  the  link  shown  in  the  cut,  the 
fralve  has  its  shortest  travel.  The  further  removed 
the  link  is  from  the  position  shown,  either  upward 
or  down,  the  longer  is  the  valve's  travel. 


V.  Valve  Stem. 
B.  Link  Block. 
L.  Link. 

Ki  £2.    Link  Blades. 


R.  Radius. 

S.  Shaft. 

a.  Heaviest  side  of  back- 

ward over  eccentric. 

b.  Heaviest  side  of  forward 

under  eccentric 


FOR  VALVE  SETTING  in  a  stationary  engine,  12x24 
inches,  place  the  valve  central  over  the  ports,  the 
rocker  arm  plumb,  the  heavy  side  of  the  eccentric 
plumb  over  the  shaft,  and  the  crank  pin  at  dead 
center.  See  that  the  eccentric  blades  are  con- 
nected with  the  link  and  are  in  full  gear,  forward 
or  backward.  This  will  make  the  extreme  travel 
.of  the  valve  equal  to  the  throw  of  the  eccentrics. 
If  a  lead  of  1-16  of  an  inch  is  desired,  move  the 
eccentric  in  the  direction  in  which  you  want  the 
engine  to  run,  until  your  valve  has  the  desired 


LINK  MOTION  AND  VALVE  SETTING      145 

lead.  Then  fasten  the  eccentric,  throw  the  crank 
pin  on  the  opposite  dead  center  and  if  the  lead  on 
the  opposite  port  is  then  the  same,  the  valve  is 
set.  If  it  is  not,  make  adjustments. 

The  above  covers  one  motion.  For  tfce  opposite 
motion  reverse  the  link  and  go  through  the  same 
operation  for  the  other  eccentric. 

For  convenience  an  engineer  should  tram  his 
valve-stem,  so  as  to  know  the  opening  point 
either  way  without  removing  the  valve  chest  cover. 

Q. — Why  is  a  link  placed  on  an  engine? 

A. — Because  it  is  the  most  convenient  means 
for  reversing  an  engine.  It  is  almost  a  necessity 
where  a  valve  has  much  steam  lap,  or  where 
quick  reversing  is  required. 

Q. — Which  way  does  the  engine  run  when  the 
link  is  fully  down  on  the  block? 

A. — It  would  run  under,  toward  the  cylinder. 

Q.— How  would  you  reverse  the  engine  in  that 
case? 

A. — By  pushing  it  full  up. 

Q. — How  can  a  single-eccentric  engine  be  made 
to  be  easily  reversible? 

A. — By  substituting  a  rocker  arm  with  another 
rocker  pin  above  the  center  of  rock  shaft.  (See 
page  101.) 


146  AREA    OF    STEAMPORT 


AREA   OF   STEAMPORT. 

The  area  of  the  steamport  may  be  justly  consid 
ered  as  the  basis  from  which  all  other  dimensions 
are  derived  in  conformity  with  known  laws. 

It  makes  a  difference,  whether  the  port  is  simply 
to  admit  the  steam  to  the  cylinder,  or  whether  it  is 
also  to  serve  as  exit  or  exhaust. 

In  the  latter  case  a  small  quantity  of  steam 
forces  its  way  out  with  a  constantly  diminishing 
pressure  and,  therefore,  the  exhaust  port  must  be 
larger  than  the  steam  port. 

Where  the  same  port  serves  for  both  purposes, 
it  must  have  the  proper  area  for  the  exhaust,  and 
is  opened  only  partly  for  the  admission  of  steam, 
which  enters  from  the  boiler  with  a  practically 
constant  velocity. 


NUMBER  OF  CRANK  REVOLUTIONS 
FOR  GIVEN  STROKE  AND   PISTON   SPEED. 

PISTON  SPEED  (feet  per  minute.) 


STROKE. 

200 

210 

220 

225 

230 

240 

250 

270 

300 

350 

1  ft. 

6  in. 

67 

70 

73 

75 

76 

80 

83 

90 

100 

116 

1   " 

8  " 

60 

63 

66 

68 

70 

72 

75 

81 

90 

105 

1   " 

10  " 

55 

57 

60 

61 

63 

66 

68 

74 

82 

96 

2  " 

6  " 

40 

42 

44 

45 

46 

48 

50 

54 

60 

70 

3  " 

0  " 

33 

35 

36 

37 

38 

40 

42 

45 

50 

58 

4  " 

0  " 

25 

26 

27 

28 

29 

30 

31 

34 

38 

44 

5  " 

0  " 

20 

21 

22 

22 

23 

24 

25 

27 

30 

35 

HORSE   POWER 

Coal  furnishes  heat;  heat  converts  water  into 
steam;  the  steam  drives  the  piston;  the  piston 
motion  is  converted  into  rotary  motion  by  the  con- 
necting rod  and  crank  pin.  The  rotary  motion  is 
utilized  for  work.  The  amount  of  work  that  an 
engine  can  do  is  expressed  in  "horse-powers,"  the 
unit  being  determined  as  follows: 

The  usual  traveling  gait  of  a  horse  hitched  to  a 
light  sulky  is  about  5  miles  an  hour,  or  440  feet  per 
minute.  If  a  spring  scale  be  attached  to  the 
singletree  we  may  note  the  amount  of  power  the 
horse  is  exerting.  Assuming  this  to  be  75  Ibs. 
and  the  speed  440  feet,  multiplied  by  75  Ibs.  equals 
33,000  foot  Ibs.,  which  represents  a  horse-power. 
In  applying  this  to  a  steam  engine  we  first  find 
the  area  of  the  face  of  piston  head,  multiply  the 
answer  by  piston  speed  in  feet  per  minute,  and 
divide  by  33,000;  the  answer  will  be  the  indicated 
horse -power.  For  the  actual  or  effectual  horse- 
power take  2-3  of  the  quotient. 

Example:  Engine  cylinder  12x24,  speed  100 
revolutions  per  minute,  steam  80  Ibs.,  area  of 
piston  113  square  inches.  Multiply  113  by  80, 
14? 


148  QUESTIONS    AND    ANSWERS 

equals  9,040  Ibs.  pressure  on  piston  face,  by  400 
feet  piston  travel  per  minute,  equals  3,616,000, 
divided  by  33,000  equals  109  N.  H.  P.  full  opening 
of  valve,  deduct  1-3  for  cut-off,  equals  72  2-3 
actual  h.  p.  For  short  cut-off  one-half.  The 
reduction  is  made  for  average  pressure,  condensa- 
tion, friction,  etc. ,  and  will  be  found  quite  correct 
in  practice. 

Quick  rules,  such  as  are  generally  given  for  find- 
ing the  H.  P.  of  cylinders,  waterfalls,  water- 
wheels,  etc.,  are  useless. 

One  "watt"  is  the  1-746  part  of  one  horse  power. 
One  thousand  watts  or  a  "kilowatt"  equals  one 
and  one-third  horse  power.  The  watt  is  the 
practical  unit  of  electrical  activity  or  power ;  it  is 
the  rate  of  working  in  a  circuit  when  E.  M.  F.  is 
one  volt  and  the  current  one  ampere.  (See  elec- 
tricity. ) 

The  best  engines  and  boilers  develop  a  horse 
power  per  hour  by  the  consumption  of  2  Ibs.  of 
coal.  But  this  is  better  than  the  average,  and 
3  Ibs.  is  more  common. 

Q. — How  much  heating  surface  is  required  to 
develop  one  horse  power? 

A. — It  varies  with  the  purpose  of  the  plant. 

Steam  for  heating,  etc 15  sq.  ft.  heating  surface 

For  plain  throttle  engine 15     ' 

For  simple  Corliss  engine 12      ' 

For  compound  Corliss  condensing.  .10     ' 

Q. — How  many  horse  power  will  a  boiler  furnish 


HORSE   POWER  149 

for  a  plain  slide  valve  engine,  boiler  having 
1,500  square  feet  heating  surface? 

A.— One  hundred  H.  P. 

Q. — How  much  for  simple  Corliss  engine,  same 
boiler? 

A. — One  hundred  and  twenty-five  H.  P. 

Q. — For  compound  engine? 

A.— One  hundred  and  fifty  H.  P. 

Q. — Which  would  you  consider  the  best  basis  in 
comparing  boilers? 

A. — Their  evaporative  efficiency. 

Q. — Give  consumption  of  steam  per  indicated 
horse  power  per  hour  for  various  engines? 

A.  — Plain  slide  valve  engine 60  to  70  Ibs. 

High  speed  automatic  engine.  30  to  50  " 

Simple  Corliss  engine 25  to  35  " 

Compound  Corliss  engine 15  to  20  •• 

Triple  expansion  engine 13  to  17  " 

An  engine  of  the  proper  size  and  in  good  con- 
dition will  yield  one  H.  P.  at  the  lowest  consump- 
tion. 

Q. — How  would  you  determine  the  proper  size 
or  evaporating  capacity  of  a  boiler  to  supply  steam 
for  a  given  purpose? 

A.— It  is  necessary  to  consider  the  number  of 
pounds  of  dry  steam  actually  required  per  hour  at 
stated  pressure. 

Q. — What  is  the  standard  horse  power  rating 
for  any  steam  boiler  for  common  slide  valve  and 
Corliss  engine? 

A. — For  plain  slide  valve  engine  the  evaporation 


ISO  QUESTIONS   AND    ANSWERS 

is  62*6  Ibs,,  or  one  cubic  foot  of  water  per  hour  per 
horse  power,  and  for  the  Corliss  31 X  Ibs.,  or  J^ 
cubic  foot  of  water  per  hour  per  horse  power. 

Q. — How  would  you  figure  the  horse  power  for 
a  steam  boiler  of  any  size,  if  you  wish  to  run  a  so- 
horse  power  engine  for  i  hour,  carrying  60  Ibs.  of 
steam  pressure? 

A. — First  multiply  the  pressure  to  be  carried  by 
time  in  minutes,  60,  and  divide  by  30,  the  amount 
of  water  in  pounds  per  horse  power  evaporated  per 
hour. 

Q. — How  would  you  proceed  to  find  the  horse 
power  of  a  compound  condensing  engine? 

A. — The  H.  P.  of  a  compound  condensing, 
engine,  of  necessity,  cannot  amount  to  any  more 
than  the  aggregate  of  the  two  powers  produced  in 
the  two  cylinders.  Therefore  the  power  developed 
in  each  cylinder  must  be  calculated  separately  and 
the  two  results  added.  (See  indicator,  p.  154.) 

Q — What  is  good  working  vacuum  for  a  steam 
engine? 

A. — From  22  inches  upward,  when  the  barometer 
stands  at  30  inches. 

Q. — Suppose  the  M.  E.  P.  upon  the  piston  is  40 
Ibs.  per  sq.  in.,  and  the  vacuum  gauge  stands  at 
22  inches  (barometer  at  30  in.),  what  would  be  the 
total  on  one  side  of  the  piston? 

A. — 40  Ibs.  per  sq.  inch,  the  M.  E.  P. 

Q. — How  is  the  horse  power  found  of  a  non- 


HORSE    POWER  151 

condensing  compound  engine? 

A.— By  first  finding  the  average  area  of  both 
cylinders.  This  is  done  by  finding  the  area  of  the 
high  and  the  low  pressure  cylinders  •separately; 
then  add  them  both  together  and  divide  by  two. 

Q. — How  is  the  average  mean  effective  pressure 
found? 

A. — By  finding  each  cylinder's  mean  effective 
pressure,  then  adding  the  two  together  and  divid- 
ing by  two. 

Q. — After  this  is  done,  how  would  you  proceed 
to  find  the  gross  H.  P.  ? 

A.— Multiply  the  average  area  by  the  average 
mean  effective  pressure  (see  page  159),  then  by 
the  piston  travel  per  minute,  and  divide  by  33,000. 
Answer  will  be  H.  P. 

Q. — How  do  you  increase  the  power  of  an 
engine. 

A. — By  increasing  its  speed.     It  is  done: 

First,  by  increasing  the  boiler  pressure,  and, 
thereby,  the  M.  E.  P.  on  the  piston. 

Second,  by  increasing  the  boiler  pressure  *and 
decreasing  the  outside  lap  of  valve  so  as  to  cut  off 
late"  This  method  is  not  advisable. 

i  bird,  by  increasing  the  leverage  of  the  main 
shaft  pulley  by  decreasing  its  diameter. 

Fourth,  by  increasing  the  speed  of  line  shaft  or 
the  diameter  of  the  driver  pulley  on  line  shaft,  or 
by  decreasing  the  diameter  of  pulley  on  main  shaft. 


152  QUESTIONS    AND    ANSWERS 

Q.—  Give  the  rule  for  finding  the  horse  power  of 
a  belt's  transmission ;  also  example? 

A.— Multiply  the  width  of  the  belt  in  feet  by 
the  number  of  hundred  feet  the  belt  has  traveled 
in  one  minute.  Example :  Belt  2  feet  wide  run- 
ning 150  feet  per  minute — 2  multiplied  by  150 
equals  300  h.  p. 

Belting  horse  power  of  a  belt  equals  velocity  in 
feet  per  minute,  multiplied  by  the  width.  One 
inch  in  length  of  single  belt  moving  at  1,000  feet 
per  minute  per  i  inch  width  equals  i  h.  p.  For 
double  belts  of  great  length  over  large  pulleys 
allow  about  500  feet  per  minute  per  i  inch  of  width 
per  horse  power.  Power  should  be  communicated 
through  the  lower  running  side  of  a  belt,  the  upper 
side  to  carry  the  slack. 

The  average  breaking  weight  of  a  belt  3-16x1 
inch,  single  leather,  is  530  Ibs. ;  three -ply  rubber 
belt,  600  Ibs.  The  strength  of  a  belt  increases 
directly  as  to  its  width.  The  allowance  for  safety 
for  rubber  belts  is  ^  and  for  leather  belts  1-16 
(breaking  weight)  in  lacing. 

Q. — Can  you  give  a  short  rule  for  finding  the 
H.  P.  of  tubular  boilers,  and  are  such  rules  of  value? 

A. — They  are  not.  A  short  rule  to  find  the 
horse  power  of  a  tubular  boiler  is :  Multiply  the 
square  of  diameter  in  £ eet  by  length  and  divide  by 
constant  .4.  For  flue  boiler  multiply  diameter  of 
shell  in  feet  by  length  and  divide  by  .4,  or 


HORSE   POWER 


IS3 


multiply  area  of  grate  surface  in  square  feet  by 
i^.     The  answer  gives  the  horse  power. 

Table    Giving  Horse   Power  of  Boilers  of  the 
Usual  Sizes. 


Diameter 
Shell. 
Inches. 

"Srjti 

ffi 

Number 
Tubes. 

5«  . 

Ill 

Diameter 
Tubes.. 
Inches 

Heating 
Surface. 
Square  feet. 

Horse  Power 
60  Ibs. 
Pressure. 

72 
72 
72 
72 

18 
16 
16 
15 

70 
90 
112 
112 

18 
16 
16 
15 

4 
3V2 
3 
3 

1502 
1472 
1496 
1400 

100 

98 
99 
93 

60 
60 
60 
00 

18 

17 
16 
16 

65 
65 
65 
80 

18 

17 
16 
16 

XXX 

co  co  co  co 

1200 
1148 

1075 

1088 

80 
76 
72 
72 

54 
54 
54 
54 

18 

17 
16 
16 

50 
50 
50 
60 

18 

17 
16 
16 

3/2 

31A 
3 

951 
900 

795 
832 

63 
60 

53 

55 

CO  00  CO  CO 

16 
16 
15 

14 

40 
49 
49 
49 

16 
16 
15 
14 

3/2 

3 
3 
3 

683 
684 
642 
600 

46 
46 
43 
.40 

42 
42 
42 
42 

15 
14 
13 

12 

38 
38 
38 
38 

15 

14 
13 

12 

3 
3 
3 
3 

508 
476 
441 
408 

34 
32 
30 
27 

42 

42 

42 

II 
10 

9 

45 
45 

45 

II 
IO 

9 

2K 
2*4 
2/2 

390 
355 
320 

26 
24 

22 

THE  INDICATOR 


Q. — What  is  an  indicator? 

A.  — It  is  an  instrument  which  records  the  varia- 
tions of  pressure  during  the  length  of  one  stroke. 
Q. — Can  you  describe  the  instrument? 
A. — A  small  cylinder  of  exactly  %  sq.  inch  inside 
diameter  is  connected  to  both  ends  of  the  steam 
cylinder,  but  steam  is  admitted  from  one  end  at  a 
time  only.     In  the  small  cylinder  moves  a  piston, 
whose  crosshead  works  a  pair  of  light  levers,  the 
free  end  of  which  holds 
a  pencil,  which  marks  its 
path  of  motion  on  a  paper 
clamped   on  a  revolving 
I  drum. 

Q. — How  is  the  stroke 
I  of  the  instrument's  pis  ton 
regulated? 

A. — By  a  spring  of 
known  tension.  A  set 
of  such  springs,  each 
marked  with  the  pressure 

for  which  it  is  intended,  accompanies  each  instru- 
ment, as  follows: 

For  pressure  up  to  21  Ibs.  per  sq.  inch  use  15  Ib.  spring. 

(I  li  tt          4«        38         4.  4'  44  4»      2Q 


1    94 
1  143 


30 
50 


154 


THE   INDICATOR 


155 


Q. — What  makes   the   indicator   card   revolve^ 

A.— A  carefully  adjusted  cord,  indirectly  con 
nected  to  the  crosshead  of  the  engine. 

Q.  — How  do  the  pencil 
tracings  on  the  paper  convey 
information? 

A.  —  For 
an  in  tell  i- 
,  gent  read- 
ing of  the 
diagram 
one  should 
compare  it 
with  the  line 


the     pencil 

perfect  con- 

Q.— How 


would  trace  under 

ditions. 

would     you     con- 


struct such  a  perfect  line? 

A. — Assuming  an  engine  to  have  a  32"  stroke,  60 
Ibs.  steam  (gauge pressure),  vacuum  12  Ibs.,  cutting 
off  at  8",  exhaust  release  2"  from  end  of  stroke, 
and  compression  (exhaust  closure)  5"  from  com- 
pletion of  stroke, — I  should  lay  off  these  figures 
on  a  "cross-section"  sheet.  (Fig.  i  shows  the 
cross-section  in  the  margin  only,  to  give  a  clearer 
cut.  Only  the  principal  lines  are  drawn  all  across. ) 

Mark  off  32  spaces,  each  to  represent  i"  of 
stroke,  horizontally,  calling  the  starting  point  at 
the  left  o  and  the  end  at  the  right  32.  Mark  off 


'56 


THE    INDICATOR 


vertically  25  spaces,  each  to  represent  3  Ibs.  of 
pressure.  The  upper  limit  of  the  fifth  space 
(starting  from  the  o  point  first  mentioned)  will 


JNfinD 


RELEASE  LINE 


NOISSIMOV 


imssn 

XUH 


JLL 


\  I  I, I 


FIG.    I 


then  be  atmospheric  line  (3x5=15),  5  spaces 
further  will  be  the  15  -Ib.  steam  pressure  line,  and 
so  on,  the  last  line  representing  the  6o-lb.  pressure. 


THE    INDICATOR  157 

Steam  enters  in  our  case  during  %  of  the  stroke, 
therefore,  we  make  the  "steam  line"  8  spaces 
long  on  the  60 -Ib.  line,  starting  from  the  o 
vertical.  At  the  end  of  the  steam  line  the  supply 
is  cut  off,  expansion  begins  and  pressure  is 
reduced,  first  rapidly,  then  more  and  more 
slowly  (in  an  inverse  ratio  to  the  volume;  at 
point  1 6  the  volume  has  been  doubled  and  the 
pressure  halved).  This  gives  an  evenly  curved 
line  down  to  the  intersection  of  the  vertical  30  (2° 
from  end  of  stroke)  with  the  horizontal  indicating 
6  Ibs.  of  pressure  (2  spaces  above  the  atmospheric 
line).  At  this  point  (point  of  release)  the  release 
(exhaust)  valve  should  open,  and  the  pressure 
sink  again  rapidly  down  to  nothing  (atmospheric 
line)  and  below,  represented  by  a  short,  sharp 
curve  between  the  verticals  30  and  32  and 
a  straight  line  along  the  vertical  32,  4  spaces 
to  the  exhaust  line  (release  line,  or  vacuum  , 
line). 

The  engine  piston  travels  then  27  inches  in  the 
opposite  direction,  while  the  exhaust  valve'  keeps 
open  (exhaust  line)  to  the  "point  of  compression" 
where  the  not  exhausted  steam  begins  to  be  com- 
pressed until  during  the  last  5  inches  of  the 
piston's  travel  the  pressure  is  gradually  brought 
up  to  atmospheric  pressure.  The  "compression 
line"  representing  this  is  an  upward  curve  ending 
at  the  intersection  of  the  atmospheric  line  and  the 


'5* 


QUESTIONS    AND    ANSWERS 


zero  vertical.  At  this  point  steam  is  admitted, 
raising  the  pressure  instantly  to  60  Ibs.,  shown 
on  the  diagram  by  a  straight  line  along  the 
vertical  zero  up  to  the  6o-lb.  horizontal.  This 
completes  the  diagram. 

Q. — Does  the  diagram  taken  on  engines  deviate 
much  from  this  model  just  described?  and  if  so,  why? 
A.  —  There   are   great 
deviations,    caused     by 
v          leaks,   wrong    lead,    late 
fv  valves,  light  load 

>v  with  heavy  com- 

pression, etc. 


60 


ATMOSPHERE  LINE. 
FIG.    2 

(The  broken  lines  in  the  cut  give  examples  of 
diagrams  indicating  imperfections  in  the  cylinder 
or  valves,  while  the  outline  is  a  nearly  perfect 
specimen  of  diagram  above  atmospheric  line  ) 

Q. — What  is  the  purpose  of  an  indicator  card? 

A. — It  serves  as  a  guide  in  setting  the  valves, 
as  a  help  (in  connection  with  a  feed-water  test  for 
steam -consumption)  in  determining  the  economy 
with  which  an.  engine  works,  and  especially  for 
finding  the  MEAN  EFFECTIVE  PRESSURE  of  an  engine. 

Q. — How  do  you  figure  the  M.  E.  P.  from  an 
indicator  card? 


THE    INDICATOR 


159 


A. — Divide  the  extreme  length  of  the  diagram  in 
10  equal  spaces  vertically  by  9  dotted  lines  (Fig.  2), 
and  divide  each  space  into  vertical  halves  by  full 
lines.  The  length  of  these  10  vertical  lines 
(ordinates)  inside  the  diagram  indicates  the  M. 
E.  P.  for  each  space.  Add  these  10  lengths 
together,  and  divide  their  sum  in  inches  by  10. 
Multiply  the  quotient  by  the  scale  of  the  spring 
used  in  the  indicator,  and  the  product  will  be  the 
M.  E.  P.  throughout  the  stroke. 

Many  engineers  mark  the 
ordinates  only,  in  Fig.  3  the 
dotted  lines  marked  O. 
The  broken  line  G  shows 
a  lazy  valve  opening. 
Notice  that  the  ordi- 
nates   are    measured 
from  the  atmospheric 
line,  not  from 
the  vacuum 
.    ^  line. 

f 


FIG.    3 

Q. — Why  do  you  multiply  by  the  scale  of  the 
spring? 

A. — Because  one  inch  of  height  in  the  diagram 
represents  the  amount  of  pressure  indicated  on 
the  spring,  two  inches  the  double,  etc. 

Q. — Is  there  a  quick  way  of  figuring  the 
M.  E.  P.? 


i6o 


QUESTIONS    AND    ANSWERS 


A. — Yes.  Make  a  rough  sketch  of  a  diagram 
and  divide  the  length  of  it  into  10  equal  spaces; 
allow  for  the  first  four  spaces  (to  cut-off)  the  full 
pressure  as  per  gauge,  say  100  Ibs.  each,  divide 
their  sum,  400,  by  5,  the  number  of  the  next  space, 


100 


100 


100 


100 


80 


ORD1NATES 


66.4 


57.1 


allowing  the  quotient,  80,  for  the  fifth  space; 
then  divide  the  same  sum,  400,  by  6  and  allow 
this  quotient  for  the  sixth  space,  and  so  on,  to 
the  last  space.  Add  all  these  figures  together, 
and  divide  by  10  and  proceed  as  above.  (See 
cut.) 

Q. — Is  this  a  very  accurate  way? 

A. — No,  but  it  will  answer  for  a  rough  figuring 
under  ordinary  circumstances. 

Q. — How  is  the  PANTOGRAPH  used  in  connection 
with  the  indicator? 

A. — One  end  of  it  (C)  is.  fixed  to  the  crosshead, 
the  other  (D)  is  made  stationary  by  a  fixed  stake 


THE    INDICATOR 


161 


placed  in  line  with  the  crosshead  socket  at  mid- 
stroke.  A  peg  (F)  is  placed  in  one  of  the  holes  on  the 
adjustable  strip  G,  so  as  to  be  on  the  line  between 


the  two  points  C  and  D,  and  at  such  distance 
from  C  that  the  cord  connecting  it  with  the 
indicator  drum  will  be  parallel  with  the  guides. 


The  peg  will  not  move  as  fast  as  the  piston  head, 
but  it  moves  at  exactfy  the  same  ratio,  giving  an 
accurate  diagram.  (See  cuta) 


162  QUESTIONS  AND  ANSWERS 


INDICATOR  EXAMINATION 

Q. — Can  any  one  use  the  indicator  intelligently? 

A.— No,  only  one  who  has  had  experience  with 
engines,  who  possesses  power  of  observation,  and 
who  is  familiar  with  measurements  and  calcula- 
tions. 

Q.— What  length  can  a  diagram  be? 

A. — As  long  as  the  circumference  of  the  drum. 

Q.— What  do  the  length  and  the  height  of  the 
diagram  represent? 

A. — The  length  represents  the  length  of  the 
stroke.  The  diagram  is  one  inch  high  for  every 
15  or  20,  etc.,  Ibs.  pressure,  according  to  the 
spring  scale. 

Q. — If  the  30  Ibs.  spring  is  used  and  the  diagram 
is  2^  inches  high,  what  does  this  indicate? 

A. — It  would  indicate  that  the  greatest  pressure 
during  the  stroke  (steam  line)  was  2l/%  times  30 
Ibs. 

Q.— Would  the  15  Ibs.  spring  answer  in  this  case? 

A. — No.  The  pressure  would  be  63^  Ibs., 
while  the  1 5  Ibs.  spring  is  not  able  to  act  under  a 
pressure  of  more  than  21  Ibs. 

Q. — Explain  the  steam  line? 

A. — It  runs. from  the  place  of  admission  to  begin- 
ning of  cut-off. 

Q. — Where  is  the  exhaust  liner 


THE    INDICATOR  163 

A. — It  begins  at  the  point  of  exhaust  or  release. 

Q. — Which  is  the  expansion  line? 

A. — It  is  the  curved  line  between  the  cut-off  and 
the  point  of  exhaust. 

Q. — What  is  the  vacuum  line? 

A. — A  straight  line,  laid  out  by  measuring  down 
from  the  atmospheric  line  a  distance  equal  to  pres- 
sure of  atmosphere,  as  shown  by  the  barometer. 

Q. — Does  this  line  indicate  a  real  vacuum? 

A. — No,  it  indicates  a  reduction  of  the  atmos- 
pheric pressure. 

Q. — What  points  does  an  indicator  card  show? 

A. — The  high  and  low  pressure,  cut-off  and  lead, 
exhaust  point  and  atmospheric  point. 

Q. — How  does  the  steam  line  show  on  a  card 
when  steam  is  wire  drawn? 

A. — It  falls  as  the  piston  advances. 

Q. — What  is  meant  by  wire  di awing? 

A. — It  is  reducing  the  pressure  by  choking. 

Q. — When  should  the  atmospheric  line  be  taken 
on  the  card  by  indicator? 

A. — Immediately  after  the  card  has  been  taken. 

Q._Why? 

A. — Because  the  spring  in  cooling  will  change 
the  position  of  the  pencil  point. 

Q. — How  is  the  atmospheric  line  drawn? 

A. — By  holding  the  pencil  lightly  against  the 
card,  taking  care  not  to  get  it  out  of  its  true  posi- 
tion, and  then  revolving  the  drum  with  the  hand. 


164  QUESTIONS    AND    ANSWERS 

Q. — What  is  an  ordinate? 

A. — It  is  the  length  of  a  line  showing  the  height 
of  a  point  above  a  level  or  line. 

Q. — How  many  ordinates  are  marked  on  a 
diagram? 

A. — You  may  mark  any  number.  The  larger 
the  number  the  more  accurate  will  be  the  result. 
Ten  is  the  number  usually  taken  for  ordinary 
purposes. 

Q. — Where  do  you  place  the  ordinates? 

A. — In  the  middle  of  the  ten  equal  spaces  into 
which  I  divide  the  diagram. 

Q. — What  does  each  single  ordinate  show? 

A. — It  indicates  the  mean  effective  pressure 
during  the  time  in  which  the  pencil  passes  across 
the  space,  in  the  middle  of  which  the  ordinate 
lies. 

Q. — What  is  meant  by  "mean"? 

A. — If  the  pressure  was  60  Ibs.  on  entering  a 
space  and  ran  down  evenly  to  55  Ibs.  on  leaving 
the  space,  57^  Ibs.  would  be  the  half-way  between 
the  two,  or  the  "mean,'*  which  may  be  safely 
called  the  pressure  all  across  the  space. 

Q. — After  the  card  has  been  properly  laid  out, 
what  should  be  done? 

A. — Measure  the  combined  length  of  all  the 
ordinates,  divide  their  sum  by  the  number  of 
ordinates,  and  multiply  the  quotient  by  the 
figure  on  the  spring  scale  in  use. 


THE   INDICATOR  165 

Q. — How  do  you  "add"  the  ordinates? 

A. — By  laying  them  off  in  one  continuous 
straight  line  on  a  cardboard,  then  measuring  their 
total  length  in  inches. 

Q.  — Suppose  the  total  length  of  the  ten  ordinates 
were  8  inches  and  the  spring  used  was  a  50  scale, 
how  would  you  proceed? 

A. — The  eight  inches  and  10  ordinates  equals 
eight-tenths,  or  .  8,  multiplied  by  50  scale  equals 
40  pound  mean  effective  pressure  in  the  cylinder  of 
engine. 

Q. — Does  the  indicator  allow  for  all  friction, 
etc.? 

A.— Yes. 

Q.  — How  are  the  ordinates  measured,  when  the 
expansion  line  drops  below  the  atmospheric 
line? 

A. — The  sum  of  the  lengths  below  the  atmos- 
pheric line  is  subtracted  from  the  sum  of  those 
above.  Otherwise  the  calculation  is  the  same. 

Q.  — What  does  the  scale  number  on  an  indicator 
card  mean?  t 

A. — It  indicates  what  pressure  will  lift  the  pencil 
point  one  inch.  (See  cut,  page  156.) 

Q. — What  is  meant  by  mean  effective  pressure? 

A. — It  means  the  average  pressure  of  steam  in 
the  cylinder  during  one  stroke,  minus  the  back 
pressure. 


THE  COMPRESSED  NON-VIBRATING  AIR 
OR  STEAM  ENGINE 

CAN  BE    USED  TO  PROPEL    HORSELESS    CARRIAGES, 
YACHTS,  MOTOR  WAGONS,  ETC. 

The  growing  demand  for  a  small  engine,  more 
particularly  for  traction  and  marine  work,  simple 
in  construction  and  operation,  economical,  non- 
vibrating,  light  weight,  yet  strong  and  compact, 
and  reversible  by  simply  shifting  the  valves,  has 
resulted  in  the  perfection  of  an  engine  far  in 
advance  of  anything  heretofore  made  for  the 
purpose. 

One  of  the  more  essential  requirements  for  the 
above  purposes  is :  Sufficient  strength  to  start  a 
given  load  from  a  standstill,  \vhich  must  be 
greater  than  the  force  necessary  to  overcome 
ordinary  obstacles  when  in  motion. 

The  "compressed  air  engine"  develops  extreme 
power  for  its  weight  and  the  space  it  occupies.  It 
also  dispenses  with  all  vibration,  which  heretofore 
has  been  the  great  trouble  in  locomotion  of  horse- 
less carriages,  etc. 

DESCRIPTION:  The  cylinder,  as  seen  in  follow- 
ing cut,  has  2  ports,  3  pistons,  i  stuffing  box,  i 
crosshead  and  slide  for  same  and  connecting  rods 
to  a  double  crank  arm  shaft.  No  cylinder  heads. 

This  construction  makes  no    difference    in    the 
166 


THE   COMPRESSED   NON-VIBRATING  AIR   OR   STEAM 
ENGINE 


A  A,  Bedplate;  B  B,  Double  Cranks  and  Shafts; 
C  C,  Cylinder;  D  D,  3  pistons;  E  E,  Center 
Piston  Rod  and  Connecting  Rod;  F  Fi  F2  FS, 
Four  Connecting  Rods;  I,  Eccentric;  J,  Eccentric 
Rod;  K,  Engine  Tube  Frame.  The  steam  chest 
does  not  show,  being  behind  the  cylinder. 
167 


l68         NON-VIBRATING  AIR  OR  STEAM  ENGINE 

action,  but  it  does  in  the  results  obtained.  The 
two  outside  pistons  are  fastened  together  so  as  to 
move  in  the  same  direction,  and  are  connected  to 
one  side  of  the  crank  shaft.  The  center  piston, 
acting  between  these  two,  is  connected  centrally 
between  two  cranks  and  always  moves  in  the 
opposite  direction  from  the  two  outside  pistons. 
It  travels  between  the  two  ports,  first  meeting 
the  lower  piston  at  lower  port,  then  reversing  and 
meeting  the  upper  piston  at  the  upper  port,  the 
two  outside  pistons  always  traveling  outside  of  the 
two  ports,  thus  answering  the  purpose  of  the  two 
cylinder  heads,  which  are  simply  converted  into 
movable  heads  or  pistons. 

In  a  starting  pull,  the  same  charge  of  steam  or 
air  acting  on  both  pistons  at  the  same  time  gives 
twice  the  power  at  starting  and  a  double  expansion 
for  the  balance  of  the  stroke.  The  ports  and 
exhaust  are  the  same  in  construction  and  opera- 
tion as  standard  makes  of  engines  on  the  market, 


.  MENDING  A   BAND   SAW 

Bevel  both  ends  of  the  saw  the  length  of  two 
teeth.  Fasten  the  saw  in  brazing  -  clamps,  with 
the  backs  against  the  shoulders.  Wet  the  joint 
with  solder  fluid  (or  with  a  lump  of  borax  rubbed 
into  a  creamy  paste  with  a  teaspoonful  of  water  on 
a  slate).  Put  a  piece  of  silver  solder  of  the  shape 
of  joint  in  the  joint,  and  clamp  with  tongs  heated 
to  a  light  red  heat.  As  soon  as  the  solder  fuses, 
blacken  the  tongs  with  water  (taking  care  not  to 
get  any  water  on  the  saw),  release  tongs  and 
smooth  the  joint  by  hammering  and  draw-filing. 


MISCELLANEOUS 

QUESTIONS  AND  ANSWERS 

ON  THE  ENGINE 


TRAVEL   OF   CRANK   PIN  AND   CROSSHEAD 

Q.— Do  crank  pin  and  crosshead  travel  at  an 
even  gait  during  one  revolution  of  the  disc? 


A.— They  do  not.  The  diagram  shows  (i)  that 
the  crosshead  travels  only  a  very  short  distance 
while  the  crank  pin  moves  15  degrees  (}4  of  90°,  a 
quarter  revolution)  upward  from  the  dead  center ; 
(2)  that  the  distance  traveled  by  the  crosslaead 
increases  in  each  of  the  5  following  spaces,  each 
of  them  corresponding  to  the  crank  pin's  travel  of 
1 5  degrees  (6xi  5°  =  90°) ;  (3)  that  the  crosshead  has 
traveled  more  than  one-half  of  its  stroke  (the  half- 
way point  is  indicated  by  a  dotted  line  in  the  cut), 
when  the  crank  pin  has  traveled  90°,  or  %  revolu- 
tion. 

169 


170 


MISCELLANEOUS 


QUESTIONS    AND    ANSWERS 


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172  MISCELLANEOUS 

Q. — Is  a  heavy  disc  or  a  fly  wheel  of  service  in 

this  connection? 

A. — Yes,  it  serves  to  make  the  speed  in  a  revolu- 
tion more  even,  so  that  the  shaft  revolves  steadily, 
while  the  unevenness  of  motion  is  put  on  the 
piston. 

Q. — What  other  purpose  does  a  fly  wheel  serve? 

A. — It  serves  to  overcome  the  dead  centers, 
where  the  piston  can  neither  push  nor  pull. 

Q. — Does  a  crosshead  stand  still  at  dead  center 
points? 

A. — No.  The  crosshead  center  could  stand  still 
only  if  the  crank  pin  moved  around  it  as  the 
center.  The  following  cut  shows  how  the  reality 
differs  from  such  a  case. 


H,  Hi  are  the  positions  of  the  crosshead  pin 
center  when  the  crank  pin  center  is  at  D,  Di.  The 
circle  shows  the  real  movement  of  crank  pin ;  the 
two  curves  indicate  the  circles  in  which  the 
crank  pin  would  have  to  travel  as  long  as  the 
crosshead  stood  still. 


QUESTIONS    AND    ANSWERS  173 

The  movement  near  the  dead  centers  is  com- 
paratively slow,  but  as  the  crank  pin  does  not 
stand  still  at  the  dead  center,  but  is  moving  either 
toward  it  or  away  from  it,  the  crosshead,  moving 
with  it,  does  not  stand  still  either.  The  dead 
center  is  an  imaginary  point,  having  no  dimen- 
sions; thus  it  cannot  be  said  that  the  crank  pin 
center  remains  at  the  dead  center  point  any  time, 
or  that  it  takes  the  crosshead  any  time  to  change 
its  direction  of  stroke. 

Q. — Can  you  illustrate  this  fact? 

A. — Yes.  The  pendulum  of  a  clock  does  not 
stand  still  at  either  end  of  its  arc  of  oscillation. 
No  time  intervenes  between  the  end  of  one  year 
or  month  or  hour  and  the  beginning  of  the  next. 

Q. — Do  the  connecting  rod  brasses  wear  the 
crank  pin  evenly  all  around? 

A. — No,  in  running  "over"  only  one-half  of  the 
circumference  of  the  crank  pin  is  pushed  and 
pulled,  while  in  running  under  it  is  the  other  naif. 
(In  the  full  page  cut  the  half  affected  in  running 
"under"  is  shaded;  the  half  affected  in  running 
"over,"  the  direction  indicated  by  the  arrows,  is 
not  shaded.) 

Q.— Why  are  horizontal  engines  (stationary) 
generally  run  over  and  not  under? 

A. — So  the  thrust  will  be  downward  upon  the 
foundation  rather  than  up  against  the  caps  of  the 
boxes  and  the  upper  guides. 


174  MISCELLANEOUS 

Q. — How  much  farther  does  the  crank  pin  travel 
than  the  crosshead  each  revolution? 

A. — One-half  farther.  The  crosshead  moves 
twice  the  diameter  of  the  disc  (back  and  forth), 
while  the  crank  pin  travels  around  the  circum- 
ference (=  3.1416  times  the  diameter);  3  is  more 
than  2  by  half. 

Q. — Does  a  crank  pin  have  a  tendency  to  flatten 
on  one  side,  or  on  both  sides,  traveling  in  one 
direction? 

A. — Simply  on  one  side.  The  push  and  pull  of 
the  rod  is  on  one-half  of  the  pin  only,  as  the  pin 
turns  with  the  crank,  wheel  or  disc. 

HEAT 

Q. — Is  heat  a  substance? 

A. — No.  Scientists  say  now  it  is  the  energy  of 
molecular  action. 

Q. — What  are  molecules? 

A. — The  smallest  possible  parts  into  which  any 
substance  can  be  divided  without  losing  its 
chemical  identity. 

Q. — What  is  meant  by  "absolute  zero"? 

A. — The  absolute  cessation  of  molecular  action. 

Q. — When  heat  is  applied  from  outside  to  a 
substance,  what  are  the  effects? 

A.— The  substance  increases  in  temperature, 
changes  its  volume^  and,  at  certain  degrees  of 
temperature,  changes  its  form.  (See  page  180.) 


QUESTIONS    AND    ANSWERS  175 

Q.— What  is  meant  by  "latent  heat"? 

A. — In  expanding,  gases  take  heat  from  their 
surroundings.  This  amount  of  heat  does  not 
increase  the  temperature  of  the  expanding  gas, 
and  is  therefore  not  measurable  by  the  ther- 
mometer. Any  heat  expended  in  this  or  a  similar 
way,  and  not  "sensible,"  or  "noticeable  to  the 
feeling,"  is  called  latent  heat. 

Q. — How  is  sensible  heat  measured? 

A. — By  means  of  a  thermometer. 

Q. — How  is  a  thermometer  constructed  and 
graduated? 

A. — A  glass  tube  with  bulb  at  closed  end  is 
partly  filled  with  mercury,  and  heated  until  the 
mercury  overflows.  Then  the  open  end  is  closed 
by  fusing,  and  when  cooled,  the  bulb  is  placed  in 
melting  ice  and  the  point  to  which  the  mercury 
falls  is  marked  the  freezing  point,  32  deg.  Then 
place  it  in  boiling  water  which  is  exposed  to  the 
open  air  and  when  the  mercury  rises  to  its  full 
height,  mark  it  212  deg.,  or  boiling  point.  The 
distance  between  the  two  points  is  180  deg.  . 

Q. — What  causes  the  mercury  to  rise  and  fall? 

A.  — Expansion  and  contraction. 

MEASUREMENTS   AND    CALCULATIONS 

Q. — Give  a  general  rule  for  determining  the 
sizes  of  piston  rods  for  steam  engines? 

A. — They  should  be  1-6  the  diameter  of  the 
piston-head.  t 


1 76  MISCELLANEOUS 

Q. — Does  this  rule  answer  for  all-sized  cylinders? 

A.  — No ;  only  sizes  ranging  from  4  inches  up  to 
28-inch  cylinders.  For  sizes  above  28  inches  the 
piston  rods  are  smaller  in  proportion. 

Q. — Suppose  there  were  2  pounds  of  steam  in  the 
cylinder,  how  much  pressure  would  there  be 
between  the  'piston  head  face,  valve  face  and 
cylinder  head?  Explain  by  rule? 

A. — Rule:  First  find  the  area  of  piston  and 
multiply  by  pressure  in  cylinder. 

Q. — What  is  the  meaning  of  the  term  "clear- 
ance" in  an  engine  cylinder? 

A. — The  unoccupied  space  between  the  valve 
face,  cylinder  head  and  piston  head  at  each  end 
of  the  stroke. 

Q. — Which  end  of  the  cylinder  has  the  most 
power? 

A. — The  end  without  the  piston  rod. 

Q. — Explain  why  so? 

A. — Because  the  steam  has  more  square  inches 
to  act  upon  in  the  end  without  the  piston  rod. 

Q. — How  would  you  know  the  safe  pressure  to 
carry  in  a  boiler  }&  inch  steel,  42  inches  diameter, 
and  50,000  Ibs.  tensile  strength? 

A. — First  multiply  thickness  of  shell  by  full 
tensile  strength  and  divide  by  half  the  diameter 
(radius),  and  divide  by  6,  which  gives  the  safe 
pressure  allowed  by  U.  S.  if  welded.  If  boiler 
shell  is  double  riveted  multiply  by  .70  (==  70  per 


QUESTIONS    AND    ANSWERS  177 

cent),  in  single  riveted  multiply  by  .56  (=  .56  per 
cent). 

Q. — What  is  understood  by  a  unit? 

A. — The  basis  of  measurements,  such  as  the 
day  for  measurements  of  time;  the  dollar  for 
money;  the  atmosphere  (14.7  Ibs.  per  sq.  inch) 
for  pressure;  the  caloric  (heat  required  for 
raising  temperature  of  one  Ib.  of  water  one 
degree)  for  heating;  the  horse-power  (33,000  Ibs. 
raised  one  foot  high)  for  energy;  the  volt  for 
electromotive  force,  etc. 

Q. — What  is  a  "thermal  unit"? 

A. — The  amount  of  heat  found  necessary  to 
raise  or  lower  a  pound  of  water  i  degree  (Fahr.) 
of  temperature. 

Q. — What  is  meant  by  positive  and  negative 
heat? 

A. — The  former  means  the  work  of  actual  heat- 
ing ,  the  latter  means  the  work  done  in  cooling. 

Q. — How  is  the  weight  of  the  atmosphere  found? 

A. — By  the  barometer. 

Q. — How  does  it  show?  • 

A. — Air,  being  a  substance,  has  weight.  The 
atmosphere  surrounding  the  earth  presses  at  sea 
level  with  an  average  weight  of  14. 7  Ibs.  per  sq. 
inch.  This  atmospheric  pressure  balances  a 
column  of  mercury,  in  the  vacuum  arm  of  a 
siphon,  of  about  30  inches  height.  As  the  air  rises 
(when  heated,  as  in  summer  over  a  sandy  plain) 


178  MISCELLANEOUS 

or  sinks  (when  cold  or  heavy  with  moisture),  we 
have  lower  or  higher  pressure  and  the  barometer 
indicates  this  by  the  lower  or  higher  position  of 
the  top  of  the  mercury  column  in  the  vacuum  tube. 
For  better  indication  the  scale  is  generally 
attached  to  the  open  arm,  which  is  made  very 
narrow  so  as  to  show  greater  differences. 

Q. — How  much  does  the  whole  atmosphere 
weigh? 

A. — It  is  estimated  at  five  trillions  of  tons,  the 
weight  of  a  solid  leaden  ball  of  60  miles  diameter. 

Q. — How  large  should  the  stack  be  in  proportion 
to  the  area  of  the  tubes  or  flues  combined  of  a 
stationary  boiler? 

A. — The  stack  should  be  about  25  per  cent,  or  # 
larger  in  area  to  do  good  work. 

Q. — How  many  square  feet  of  heating  surface  is 
generally  allowed  to  i  square  foot  of  grate  surface? 

A. — From  22.5  to  40  square  feet. 

Q. — Suppose  the  area  of  a  valve  is  known,  how 
is  the  diameter  found? 

A. — Divide  the  area  by  .7854  and  extract  square 
root — answer  equals  diameter. 

Q. — How  is  the  radius  (half  diameter)  found 
when  area  is  known? 

A. — Divide  area  by  3.1416  and  extract  square 
root — answer  equals  radius. 

Q. — How  is  the  linear  dimension  of  a  square 
found  from  the  area? 


QUESTIONS    AND    ANSWERS  179 

A. — It  is  its  square  root.     (See  page  239.) 

Q. — How  much  will  i  cubic  inch  of  cold  water 
expand  when  changing  to  steam? 

A. — About  1728  times,  or  into  i  cubic  foot. 

Q.  — How  large  should  the  diameter  of  a  pump 
cylinder  (plunger)  be  to  deliver  324  gallons  of 
water  per  minute,  traveling  100  piston  speed? 

A. — Divide  324  by  constant  4,  equals  81;  from 
this  extract  the  square  root — answer  equals  9 

inches,  diameter  of  plunger. 

• 

Q. — What  size  should  the  steam  cylinder  be  as 
compared  with  the  pump  cylinder? 

A.  — One-third  larger  in  diameter.  In  the  case 
mentioned,  it  should  be  12  inches. 

Q.—  How  much  of  the  steam  generated  in  a 
boiler  is  allowed  for  consumption  in  the  engine? 

A. — One-half  only.  With  the  usual  average  of 
70  Ibs.  steam  and  the  feed  water  at  the  temper- 
ature of  100°  P.,  each  15  square  feet  of  heating 
surface  of  the  boiler  will  evaporate  30  Ibs.  of  water 
per  hour.  The  engine  should,  therefore,  consume 
only  15  Ibs.  of  water  per  hour  for  every  15  square 
feet  of  boiler-heating  surface. 

Q. — What  if  the  boiler  is  not  capable  of  gener- 
ating double  the  amount  of  steam  consumed  by 
the  engine? 

A. — The  boiler  will  be  overworked,  which 
means  shortness  of  life,  many  repairs,  a  great 
waste  of  labor  and  fuel,  and  much  annoyance. 


MECHANICAL   REFRIGERATION  AND 
ICE  MAKING 


THE   SCIENTIFIC   PRINCIPLE 

It  is  a  well  known  fact  that  metals  expand  or 
contract  as  they  are  heated  or  cooled.  Many 
other  substances  have  the  same  quality,  and  it  is 
a  scientific  truth,  applying  to  all  substances  ca- 
pable of  expansion,  that  a  change  of  volume 
implies  either  an  absorption  of  heat  from,  or  a 
loss  of  heat  to>  the  surroundings. 

Different  substances  have  their  extremes  of 
volume  at  different  temperatures.  It  is  by  no 
means  so,  that  any  substance  will  keep  decreas- 
ing in  volume  indefinitely  as  its  temperature 
decreases,  or  that  its  volume  will  keep  increasing 
with  increasing  heat.  Water,  for  instance, 
occupies  the  smallest  space  at  39.2°  F.  (the 
temperature  found  at  the  bottom  of  deep  lakes), 
and  has  its  extreme  expansion  at  212.8°  F.  (when 
it  boils,  or,  in  other  words,  when  it  changes  from 
the  liquid  condition  to  the  gaseous).  Below  39.2° 
F.  water  expands  with  decreasing  temperature 
(this  is  why  ice  floats  and  bursts  pipes);  and 

it   cannot  be  heated   beyond    212.8°   F.,   except 
180 


REFRIGERATION    AND    ICE    MAKING      l8l 

in  a  closed  vessel,  which  serves  to  compress  the 
steam  into  a  smaller  volume. 
From   the   above   it   will   be  understood  that 

Gases  when  compressed  yield  heat 
to,  and  when  expanding  absorb 
heat  from,  their  surroundings. 

THE  APPLICATION    OF  THE   PRINCIPLE 

A  gas  which  will  rapidly  increase  its  volume 
when  surrounded  by  a  very  low  temperature, 

taking  the  heat  it  needs  for  expansion  from  the 
surroundings,  will,  therefore,  create  around  it  a 
very  cold  region. 

Scientists  have  frozen  water  in  a  bottle  placed 
in  a  fire.  The  bottle  was  wrapped  in  woollen  rags 
soaked  in  ether  or  chloroform,  which  evaporate 
so  rapidly  that  they  draw  heat  enough  from  the 
water  in  the  bottle-to  freeze  it. 

Common  air  can  be  reduced  to  a  liquid  by  the 
alternate  application  of  enormous  pressure  and  of 
cooling.  Liquid  air  boils  at  312°  below  o  F.,  a 'tem- 
perature almost  inconceivable.  Undoubtedly, 
liquid  air  will  become  a  mighty  agent  in  the  hand 
of  man  before  long.  (See  page  223.) 

Such  a  gas  is,  also,  anhydrous  ammonia,  which 
boils  under  ordinary  atmospheric  pressure  at 
28.5°  below  zero  F.  By  compressing  it  in  strong 
steel  tanks  it  is  kept  in  a  liquid  condition,  and  is 


182  QUESTIONS    AND    ANSWERS 

sold  that  way.  From  this  tank  (drum)  it  passes  as 
a  gas  (vapor),  feeding  into  a  pump,  which  com- 
presses it  again.  In  this  condition  it  enters  the 
evaporating  coils,  in  which  it  is  allowed  to 
expand  rapidly.  In  this  rapid  expansion  a  con- 
sumption of  heat  is  necessary,  and  the  required 
heat  is  taken  from  the  brine  in  which  the  coils 
are  immersed.  Then  the  expanded  vapor  is 
exhausted  into  a  condensing  tank,  the  evaporating 
coils  receive  a  new  charge  of  condensed  vapor 
from  the  pump,  and  the  operation  is  repeated.  In 
this  way  the  brine  is  kept  at  the  desired  low 
temperature.  The  brine  cannot  solidify  (freeze) 
on  account  of  the  salt  it  holds  in  solution. 

Q. — What  is  mechanical  refrigeration? 

A. — It  is  produced  by  the  evaporation  of  a 
volatile  liquid  which  boils  at  a  low  temperature, 
and  which  by  means  of  evaporating  coils,  a  con- 
denser and  a  gas  compressor,  is  brought  under 
the  control  of  the  operator. 

AMMONIA 

Q. — What  does  the  name  "anhydrous"  ammonia 
mean? 

A. — "Anhydrous"  means  "free  from  water"  or 
"dry." 

Q. — What  is  ammonia,  and  where  is  it  found? 

A. — It  is  a  gas  composed  of  i  part  of  nitrogen 
and  3  parts  hydrogen.  It  can  be  obtained  from 


REFRIGERATION    AND    ICfi    MAKING      183 

the  air,  from  sal-ammoniac,  nitrogenous  con- 
stituents of  plants  and  animals  by  process  of 
distillation.  As  a  matter  of  fact,  there  are  very 
few  substances  free  from  it.  At  present  almost 
all  the  sal-ammoniac  and  ammonia  liquors  are 
prepared  from  ammoniacal  liquid,  a  by-product 
obtained  in  the  manufacture  of  coal  gas  and  coke. 

Q. — What  are  the  properties  of  ammonia? 

A. — Pure  ammonia  liquid  is  colorless,  having 
a  peculiar  alkaline  odor  and  caustic  taste.  It 
turns  red  litmus  paper  blue.  Its  boiling  point 
depends  on  its  purity,  and  is  about  28^  deg.  F. 
below  zero  at  atmospheric  pressure.  The  purer 
the  liquid  the  lower  its  boiling  point.  Compared 
with  water,  its  weight  or  specific  gravity  at  32 
deg.  F.  is  about  fo  of  water,  or  0.625.  One  cubic 
foot  of  liquid  ammonia  weighs  39.73  Ibs.,  i  gallon 
weighs  5.3  Ibs.  One  pound  of  the  liquid  at  32 
deg.  will  occupy  21.017  cubic  feet  of  space  when 
evaporated  at  atmospheric  pressure.  The  specific 
heat  of  ammonia  gas  (heat  required  to  raise  one 
unit  of  it  one  degree  of  temperature,  as  compared 
with  the  heat  required  for  the  same  weight  of 
water,  =i. )  is  o.  50836.  Its  latent  heat  of  evapora- 
tion, as  determined  by  the  highest  authorities,  is 
not  far  from  560  thermal  units  at  32  degrees. 

Q. — What  is  a  "refrigerant"? 

A. — Anything  that  cools,  such  as  ammonia 
known  as  anhydrous  or  dry  ammonia. 


184  QUESTIONS    AND    ANSWERS 

Q. — What  is  the  ammonia  condenser? 

A.  — It  is  that  part  of  the  apparatus  in  which  the 
gas  is  cooled  and  changed  to  a  liquid. 

Q. — How  is  the  water  changed  into  ice'r 

A. — By  a  system  of  evaporating  coils  in  which 
the  liquid  ammonia  is  expanded  into  gas,  thereby 
cooling  the  space  around  by  absorption  of  the 
heat. 


ICE   MACHINE.  BEAM   PATTERN -CORLISS  ENQINE.V 

Q. — At  what  degree  does  pure  anhydrous 
ammonia  boil? 

A. — At  from  28^  to  40  deg.  below  zero.  (See 
table  of  boiling  points,  page  210.) 

Q. — What  advantage  does  this  give? 

A. — Ammonia  can  be  kept  at  its  boiling  point 
without  any  artificial" heat,  which  is  not  possible 
with  water. 

Q. — Is  ammonia  the  most  serviceable  of  all 
refrigerants? 

A. — Yes,  it  has  many  advantages  over  other 
refrigerants. 


ABSORPTION  AND  COMPRESSION  METHODS    185 

Q. — Which  standard  is  applied  to  the  amount  of 
ammonia  consumed  in  producing  cold,  weight  or 
volume? 

A.— Weight. 

x 
Q. — Is  ammonia  inflammable  and  explosive? 

A. — It  is  not  inflammable,  and  is,  therefore,  not 
explosive  in  the  sense  in  which  gunpowder  is 
explosive;  but  at  any  temperature  above  28.5 
below  zero  F.  it  is  expansive  like  dry  steam,  and 
is,  therefore,  dangerous. 

Q. — Has  ammonia  any  corrosive  effect  on  steel 
or  iron? 

A. — No;  but  on  brass  it  eats. 

Q. — Has  it  any  effect  when  mixed  with  water 
on  the  machinery  or  piping? 

A.— No. 

ABSORPTION    METHOD    AND    COMPRES- 
SION METHOD 

Q. — Can  you  describe  the  absorption  method  or 

system? 

A. — Yes,  but  it  is  very  little  used  now.  , 
The  gas,  instead  of  being  compressed  by 
mechanical  means,  is  obtained  from  a  26  per  cent 
solution  of  ammonia  in  water,  heated  in  'a  boiler 
or  still,  until  the  ammoniacal  gas  is  driven  off. 
This  gas  then  goes  through  the  cycle  of  operations 
as  described,  until,  having  done  its  work  of 
refrigeration,  it  is  conveyed  into  the  absorber. 


i86 


QUESTIONS    AND    ANSWERS 


Here  the  gas  is  brought  in  contact  with  the  water, 
called  the    mother    liquid,    from    which    it    was 


originally  extracted  in  the  still,  this  water  in  the 
meantime  having  gone  through  an  elaborate  proc- 
ess of  cooling.  The  cool  mother  liquid  rapidly 
absorbs  the  gas  and  forms  again  a  strong  solution 


ABSORPTION  AND  COMPRESSION  METHODS    187 

of  ammonia.  This  solution  is  returned  to  the  still 
by  means  of  a  pump  and  is  ready  again  to  go 
through  the  same  cycle  (round)  of  operations. 

Q. — Name  the  parts  of  an  absorption  apparatus? 

A. — Generator,  ammonia  pump,  absorber,  con- 
densing tank,  weak  liquor  tank,  equalizer,  freez- 
ing tank,  cooling  tank  and  receiver  for  ammonia. 

Q. — What  is  the  absorption  system  based  upon? 

A. — The  chemical  law  which  allows  ammonia 
to  boil  into  gas  at  28.5  deg.  below  zero,  while 
water  is  not  affected  until  212  deg.  is  reached.  By 
this  the  ammonia  and  water  are  capable  of  being 
separated  and  made  to  perform  continuous  duty. 

Q. — Is  the  compression  system  based  on  the 
same  difference? 

A. — No,  because  anhydrous  ammonia  is  used  in 
this  system.  ("Anhydrous"  means  without  water.} 

Q. — Why  is  it  called  a  compression  system? 

A. — Because  it  consists  of  alternate  compression 
and  expansion  of  the  refrigerant. 

Q. — What  are  the  different  operations  in  this 
system? 

A. — There  are  three,  namely,  ist,  compression 
of  the  gas;  2d,  condensation  of  the  gas  and  a 
withdrawal  of  the  heat  caused  by  compression; 
3d,  expansion  of  the  gas  and  absorption  by  it  of 
the  heat  from  the  surrounding  objects. 

Q. — Explain  process  of  compression? 

A. — The  refrigerating    agent   (anhydrous    am- 


l88  QUESTIONS    AND    ANSWERS 

monia)  is  furnished  in  heavy  iron  drums  and 
allowed  to  enter,  through  connecting  coils,  the 
induction  pipe  in  the  compression  pump,  from 
whence  it  is  drawn  into  the  cylinders,  where  it 
is  compressed  to  a  pressure  varying  from  125  to 
175  Ibs.  per  sq.  inch.  This  variation  of  pressure 
is  regulated  by  the  temperature  of  the  condens- 
ing water.  This  compression  produces,  by  a 
largely  increased  friction  of  the  gas  molecules 
(small  particles),  intense  heat. 

Q. — Does  the  pump  get  hot? 

A. — Yes,  cold  water  is  kept  flowing  around  it, 
to  cool  it. 

Q. — Explain  process  of  condensation? 

A. — The  compressed  gas  is  then  allowed  to 
enter  the  system  of  pipes  known  as  the  condenser, 
over  which  cold  water  is  kept  constantly  flowing 
(see  cut,  page  203).  The  cold  water  absorbs  the 
heat  generated  in  the  process  of  compression. 
The  gas  is  thus  cooled  in  its  flow  through  the 
great  lengths  of  pipe,  until  it  finally  cools  to  below 
28. 5  °  F. ,  when  it  collects  in  the  receiver  as  a  liquid. 

Q. — Explain  process  of  expansion? 

A. — The  liquefied  ammonia,  through  a  siphon, 
now  slowly  enters  the  expansion  or  evaporating 
coils,  which  are  brought  in  contact  with,  or  in 
close  proximity  to  the  objects  to  be  cooled.  As  it 
enters  these  coils  the  high  pressure  before  men- 
tioned is  reduced,  and  the  ammonia  immediately 


ABSORPTION  AND  COMPRESSION  METHODS    189 

re-expands  into  the  gaseous  condition,  absorbing 
the  heat  necessary  for  this  process  from  the  pipes 
and  through  them  from  the  surroundings.  Wher- 
ever two  bodies  of  different  temperature  are 
brought  in  contact,  the  hotter  wiU  impart  its  heat 
to  the  colder  until  the  temperatures  are  equalized. 

Q. — After  having  thus  accomplished  its  cooling 
work,  where  does  the  gas  go? 

A. — It  is  returned  to  the  compressor,  there  to 
again  begin  afresh  the  cycle  of  operations,  namely, 
compression,  condensation  and  expansion. 

Q. — Is  there  any  loss  of  ammonia  during  each 
operation? 

A. — Yes,  very  small. 

Q. — How  often  can  ammonia  be  used  in  the 
manner  just  described? 

A. — Times  without  number. 

Q. — What  is  absolutely  necessary  to  render  these 
three  operations  continuous? 

A. — Each  separate  part  of  the  machine  (appa- 
ratus) must  be  suitably  connected.  (See  testing 
and  charging. ) 

Q. — State  the  main  points  as  to  all  appliances 
and  machinery  about  a  refrigerating  plant? 

A. — Good  order  and  cleanliness  should  be  prac- 
ticed, also  pump  and  valve  tightly  packed. 

Q. — What  gives  the  greatest  trouble  about  an 
artificial  ice  plant? 

A. — Leakage. 


BRINE    SYSTEM     AND    DIRECT     EXPAN- 
SION SYSTEM 

Q. — In  what  different  ways  is  refrigeration  done? 

A. — For  lesser  degrees  of  cooling,  as  for  brew- 
eries, living-rooms,  etc.,  the  brine  system  is 
sufficient,  in  which  the  brine  after  being  cooled  by 
the  ammonia  is  pumped  through  the  pipes.  For 
very  low  temperature,  as  needed  in  cold  storage, 
direct  expansion  is  used,  allowing  the  gas  to 
expand  in  the  pipes,  which  are  placed  in  the  cool- 
ing rooms. 

Q. — Which  of  the  two  systems  is  more  expensive? 

A. — The  direct  expansion  system,  both  because 
of  the  large  amount  of  specially  made  pipe 
required,  and  because  the  whole  plant  must  be  in 
operation  day  and  night,  to  supply  liquid  ammonia 
for  expansion. 

Q. — What  advantage  has  the  brine  system  over 
the  direct  expansion  in  ordinary  conditions? 

A. — Ordinary  piping  may  be  used,  and  the  large 
body  of  brine  suffices  to  maintain  the  temperature 
desired  in  the  rooms  for  a  considerable  length  of 
time  by  merely  operating  the  brine  circulating 
pump,  it  very  frequently  being  only  necessary  to 
operate  the  compressor  in  the  daytime  to  maintain 
the  temperature  during  the  entire  twenty-four 
hours. 

Q. — Describe  the  process  of  circulation  in  the 

brine  system? 

190 


DIRECT    EXPANSION    SYSTEM  1 9! 

A. — It  is  done  by  a  special  pump  known  as  the 
brine  circulating  pump,  which  forces  it  through 
the  pipes  arranged  in  the  rooms  to  be  cooled, 
from  which  it  returns  to  the  re -cooling  tank  and 
is  used  continually  over  and  oveiv  again. 

Q. — Is  the  brine  circulation  independent  of  the 
gas? 

A.— Yes. 

Q. — Where  and  when  do  they  come  in  contact? 

A. — In  the  brine  tank  only. 

Q. — Explain  how  this  is  done? 

A.— The  cold  ammonia  gas  extracts  the  heat 
from  the  brine  as  it  flows  through  the  tank  in  the 
circulation  pipes. 

Q. — Do  the  two  circulating  systems  come  any 
nearer  than  that  just  mentioned? 

A.— No. 

Q. — What  is  the  brine  tank   in  an  ICE-MAKING 

PLANT? 

A. — It  consists  of  one  or  more  salt  water  tanks, 
in  which  the  evaporating  coils  of  pipe  are  sub- 
merged, and  the  liquid  ammonia  is  allowed  to 
expand  within,  where  it  assumes  its  original 
gaseous  condition  and  in  so  doing  absorbs  the 
heat  from  the  brine,  lowering  the  temperature  to 
any  degree  required. 

Q. — How  is  the  brine  tank  arranged  for  making 
ice? 

A. — It  is  a  covered  tank  with  many  openings  to 


™         *H 

S  S  3 


192 


DIRECT     EXPANSION    SYSTEM  193 

admit  galvanized  sheet  iron  tanks  to  hold  distilled 
water  for  freezing  into  blocks  of  clear  ice.  (See 
opposite  page;  for  model  ice  plant,  see  page  10.) 

Q. — How  long  will  it  take  the  water  in  the 
galvanized  tanks  to  freeze  a  cake  of  the  usuaj  size, 
11x22x45  inches? 

A. — It  is  according  to  the  temperature  of  the 
brine. 

Q. — If  the  brine  is  cooled  to  14  deg.  above  zero, 
how  long  would  it  take? 

A. — About  60  hours. 

Q. — Why  does  it  take  so  long? 

A. — Ice  is  a  bad  conductor;  the  ice  forming  first 
on  the  six  surfaces  communicates  the  cold  very 
slowly  to  the  water  within. 

Q. — Is  it  a  good  plan  to  freeze  the  water 
quickly? 

A. — No;  if  frozen  too  quickly  it  will  not  be 
transparent,  but  cloudy. 

Q. — What  is  meant  by  the  agitator  and  its  use? 

A. — It  is  a  centrifugal  (rotary)  pump  used  for 
drawing  the  brine  from  the  bottom  of  one  end  of 
the  tank  and  discharging  it  in  the  other  end  at  the 
top,  thereby  securing  uniform  freezing  by  con- 
tinual circulation  of  the  bath. 

Q. — How  is  the  ice  cake  taken  from  the  mold? 

A. — By  running  hot  water  over  the  can  and 
dumping  it.  (See  cuts  of  Eclipse  thawing  ap- 
paratus, next  page. ) 


MOULD  HOLDER.  "~1 
JPRIQMT  POSITION.      | 


Wooden  Dump 
ECLIPSE  AUTOMATIC  THAWING  APPARATUS 
AND  CAN  DUMP. 


194 


WATER    EXAMINATIONS 


195 


TABLE   OF   BRINE    SOLUTIONS 

(Chloride  of  Sodium,  Common  Salt) 


Percentage   of    Salt 
by  Weight 

Degrees      by     Salo- 
meterat  60P  F 

Specific  Gravity    at 
60°  F..  . , 


Weight       of 
Gallon 


One 


Pounds    of    Salt   in 
One  Gallon 


Pounds  of  Water  in 
One  Gallon 


Pounds  of  Water  in 
One  Cubic  Foot... 

Freezing    Point     in 
Degrees  F 


5 
90 

1  037 

8  65 
0  432 

8  218 


25  4 


1  037 
8  95 
0  895 
8  055 


62  172  61  465  60  253 !  59  134  57  408  55  695 


18  6     |12  2 


20 


WATER  EXAMINATIONS 

FOR   HARD   WATER,    ETC. 

Particles  suspended  in  the  water  may  be  detected 
by  filling  a  tall  glass  cylinder  and  placing  same 
on  a  clean  piece  of  white  paper  and  looking  down 
through  the  water.  All  waters  are  known* as 
hard  or  soft,  and  in  many  cases  hard  water  may 
be  made  soft  and  the  air  and  gases  be  expelled  by 
boiling,  in  which  case  it  is  called  temporary  or 
removable  hardness.  If  unaffected  by  boiling  it 
is  called  permanent  hardness,  and  nothing  short 
of  distillation  or  boiling  into  steam  and  condensing 
the  vapor  will  remove  the  cause. 


196  QUESTIONS    AND    ANSWERS 

Q. — What  is  it  that  makes  watef  hard,  and  how 
much  of  it  is  present? 

A. — Eight  grains  of  mineral  matter  (carbonate 
of  lime,  etc. )  or  more  in  a  gallon  of  water  make 
it  hard. 

Q. — How  is  the  quality  of  hardness  particularly 
noticeable? 

A. — When  soap  is  used,  the  harder  the  water, 
the  less  effect  has  the  soap,  because  the  mineral 
matter  neutralizes  so  much  of  it. 

SIMPLE   RULES  FOR    ASCERTAINING    THE    QUALITY   OF 
SO-CALLED   MINERAL   WATERS 

Water  which  will  turn  blue  litmus  paper  red 
before  boiling,  but  not  after  boiling,  is  carbonated 
(contains  carbonic  acid).  The  blue  color  can  be 
restored  by  warming. 

If  it  has  a  sickening  odor,  giving  a  black  sedi- 
ment, acetate  of  lead,  it  is  sulphurous  (containing 
sulphureted  hydrogen). 

If  it  gives  blue  settlings  with  yellow  or  red 
prussiate  of  potash  by  adding  a  few  drops  of 
hydrochloric  acid,  it  is  chalytate  (carbonate  of 
iron). 

If  it  restores  blue  color  to  litmus  paper  after 
boiling,  it  is  alkaline. 

If  it  has  none  of  the  foregoing  properties  in  a 
marked  degree  and  leaves  a  large  residue  after 
boiling,  it  is  saline  water  (containing  salts). 


THE  APPARATUS    USED    IN    THE  BRINE 
AND  IN  THE  DIRECT  EXPAN- 
SION SYSTEMS 


THE 
PUMP   VALVE 


The  induction  or  suction  valve  is  shown  closed, 
the  piston  being  on  its  upward  stroke.  Surround- 
ing the  upper  portion  of  the  valve  stem  is  se'en  a 
coiled  spring  which  raises  the  valve,  holding  it 
firmly  upon  its  seat ,  as  shown  above  and  in  sec- 
tional view  of  compressor,  page  199. 

As  the  piston  commences  its  downward  stroke 
the  pressure  of  the  gas  in  chamber  D  opens  the 

valve  and  the  cylinder  commences  to  fill. 
197 


198  REFRIGERATION 

Below  A  in  Fig.  i  is  seen  a  small  passageway 
connecting  the  gas  inlet  space  on  the  right  with  a 
small  chamber  on  its  left  formed  by  the  ring  B 
on  the  valve  stem  and  the  bore  of  the  valve  cage. 
This  passage  opens  a  little  above  the  bottom  of 
the  chamber,  and  when  the  valve  is  fully  opened 
the  ring  B  covers  the  passage,  and  the  gas  in  the 
lower  portion  of  the  chamber,  unable  to  escape, 
forms  an  elastic  cushion,  which  prevents  any 
strain  on  the  valve  stem  and  holds  the  valve  in 
perfect  equilibrium. 

The  downward  stroke  being  complete,  the 
incoming  gas  no  longer  presses  open  the  valve 
and  by  the  combined  action  of  the  spring  and 
the  imprisoned  cushioning  gas  it  is  instantly 
seated. 

The  discharge  valve  is  side  by  side  with  the 
induction  valve,  and  works  in  the  opposite  sense. 

The  requirements  of  a  good  pump  are:  To 
instantly  admit  the  gas  to  the  cylinder,  filling  it 
full  at  each  downward  stroke  of  the  piston;  to 
expel  (discharge)  the  entire  contents  of  the  pump 
through  the  outlet  valve  K,  Fig.  2,  which  opens 
as  soon  as  the  cylinder  pressure  overcomes  the 
combined  force  of  the  valve-spring  and  of  the 
pressure  in  the  condenser  beyond  the  valve 

Valves,  of  ample  area,  durable  in  construction 

and    reliable    in    action,  must    be    supplied.      A 

'  piston  is    required   that    is  perfectly    tight,    yet 


199 


2OO  THE    APPARATUS 

working  freely,  and  a  stuffing  box  for  the  piston 
rod  in  which  the  packing  can  be  readily  adjusted 
while  in  operation. 

The  stroke  of  the  piston  is  accurately  gauged 
so  as  to  reach  within  a  hair's  breadth  of  the  upper 
cylinder  head  in  order  to  force  all  the  gas  out. 

Just  above  the  lowest  position  of  the  upper  face 
of  the  piston  head  there  is  a  ring  of  8  openings  in 
the  cylinder  wall,  connecting  with  the  induction 
chamber  D.  Through  these  holes,  whose  total 
area  equals  that  of  the  induction  valve,  the  gas 
enters  at  the  lowest  position  of  the  piston  head, 
thus  securing  a  complete  filling  of  the  cylinder, 
after  the  induction  valve  has  closed.  For  the 
induction  valve,  as  shown  by  the  indicator,  admits 
only  about  three-fourths  of  the  desired  amount  of 
pressure,  because,  with  the  spring  tension,  this  is 
enough  to  balance  the  pressure  in  the  induction 
chamber. 

As  the  piston  rises  again,  it  closes  the  ring  of  8 
openings,  until  it  passes  beyond  them,  when  the 
gas  enters  once  more  through  them  to  fill  the 
vacuum  under  the  piston.  In  the  downward 
stroke,  when  the  piston  closes  these  openings,  the 
remaining  gas  under  it  is  pressed  through  small 
openings  (shown  white  in  the  cut)  at  the  bottom 
of  the  cylinder  into  the  closed  chamber  N, 
whence  it  issues  again  at  the  beginning  of  the 
upward  stroke,  working  like  a  cushion. 


PURGING  VALVE 


AMMONIA   COMPRESSION    PUMP 


202  THE    APPARATUS    USED 

THE    STUFFING    OR    PACKING    BOX 

The  leakage  of  ammonia,  even  if  so  slight  as  to 
cause  but  little  expense,  is  always  an  annoyance. 
Confined  as  it  is  in  the  pipe  system,  in  endless 
coils  without  the  possibility  of  escape,  the  only 
portions  of  the  plant  needing  careful  attention,  to 
guard  against  leaks,  are  the  stuffing  boxes  B, 
Fig.  2,  of  the  compression  pump  piston  rods  A. 

The  stuffing  box  is  of  unusual  depth,  but  with 
whatever  care  it  is  designed,  engineers  are  aware 
that  frequent  attention  is  required  in  all  machines 
to  keep  the  packing  set  up  enough  to  prevent 
leakage,  and  still  not  so  much  as  to  induce  heat- 
ing and  the  consequent  cutting  of  the  rods. 

The  stuffing  box  is  under  perfect  control  of  the 
engineer  at  all  times.  Its  geared  gland  Ci,  Fig. 
2,  connects  with  a  short  rod  F.  Turning  the 
handle  F  will  tighten  or  loosen  the  packing. 
The  engineer  can  regulate  the  pressure  upon  the 
packing  while  the  pump  is  in  motion. 

To  guard  against  the  leakage  of  ammonia,  in 
addition  to  the  very  long  stuffing  box  already 
mentioned,  a  lubricating  chamber  with  oil  pipe 
G  is  attached  for  lubricating  the  piston  rod  within 
the  packing. 

THE    AMMONIA    CONDENSER 

The  ammonia — leaving  the  compression-  pumps 
hot,  compressed,  but  still  gaseous — reaches  the 
condenser,  which  consists  wholly  of  piping  and 


IN    REFRIGERATION 


203 


should  be  conveniently  located  on  the  roof  of  the 
building.  The  condenser  should  be  divided  into 
two  parts,  namely,  the  preliminary  condenser  and 
the  liquefier,  as  shown  in  the  illustration  on  this 
page. 
The  gas  when  discharged  from  the  compressor 


AMMONIA  UQUEFICR 
WITH  PRELIMINARY  CONDENSER. 


passes  into  a  trap  where  oil.  and  other  foreign 
matters  are  deposited ;  from  the  trap  it  passes  into 
the  preliminary  condenser  (3),  which  is  located  a 
little  lower  than  the  bottom  of  the  liquefier.  After 
being  cooled  to  a  considerable  extent  in  the  pre- 
liminary condenser  the  gas  passes  through  another 
oil  trap  (i),  which  thoroughly  eliminates  even  the 


2O4  THE    APPARATUS    USED 

slightest  trace  of  oil  still  remaining  in  the  am- 
monia. When  it  is  remembered  that  the  ammonia 
supply  ought  to  do  its  work  for  a  long  period  of 
time  in  the  performance  of  the  never-ending 
cycle  of  operations,  and  that  all  foreign  substances 
act  injuriously  on  both  gas  and  machinery,  it  is 
apparent  that  it  is  of  the  most  vital  importance  to 
keep  the  gas  absolutely  free  from  all  impurities. 
This  the  additional  oil  trap  successfully  accom- 
plishes. 

Thus,  completely  purified,  the  gas  passes  out  to 
the  liquefier  (2),  where  it  is  cooled  to  a  liquid. 

The  condensing  pipes  are  cooled  by  water.  In 
the  open  air  system  the  water  drips  on  the  top 
coils  and  from  them  down  on  the  lower  ones,  until 
it  reaches  the  shallow  tank  in  which  the  prelimi- 
nary condensing  coils  are  immersed.  Thus  the 
water  is  hottest  when  it  meets  the  hottest  gases. 
A  waste  pipe  carries  the  overflow  of  hot  water  to 
the  steam  condenser. 

In  another  cooling  system,  the  condensing  pipes 
are  entirely  submerged  in  a  water  tank,  the 
water  flowing  in  at  the  bottom  and  running  out 
near  its  surface.  The  work'  of  condensing  can, 
therefore,  not  be  divided  up  as  in  the  open  air 
system. 

The  divided  form  of  condenser  possesses  marked 
advantages  and  is  a  great  improvement  over  the 
old  method  of  arrangement.  The  warmest  water 


IN    REFRIGERATION  205 

meets  the  hottest  gas,  and,  as  it  has  already  per- 
formed duty  on  the  liquefier,  it  is  used  on  the 
preliminary  condenser,  Without  expense. 

All  the  coils  should  be  made  from  extra  heavy 
special  drawn  pipe,  bent  cold,  "and  finished  coils, 
which  should  be  tester1  under  many  times  the 
pressure  they  will  ever  be  subjected  to  in  actual 
use. 

The  liquid  ammonia  flows  into  the  receiver, 
where  it  is  ready  to  perform  the  work  of  cooling 
either  by  expanding  into  coils  in  tanks  or  by 
expanding  into  coils  in  rooms  to  be  cooled. 

THE   EXPANSION    COILS 

The  ammonia,  which  left  the  compression 
pumps  and  entered  the  condenser  as  a  gas  through 
a  large  pipe,  now  leaves  the  condenser  in  a  pipe 
from  one-half  to  one  inch  in  diameter,  and  enters 
the  third  division  of  the  system,  there  again  to 
expand  into  its  original  gaseous  condition.  And 
it  is  while  expanding  to  this  gaseous  condition 
that  the  ammonia  absorbs  the  heat  from  the  sur- 
rounding objects  ere  it  returns  to  the  compressor 
to  be  again  compressed. 


SOLDER   AND    SOLDERING   FLUID 


Bar  solder:  i  Ib.  block  tin,  ^lb.  lead. 

Glazing  solder:  i  Ib.  block  tin,  i  Ib.  lead. 

Plumbing  solder:  i  Ib.  block  tin,  2  Ibs.  lead. 

For  a  good  soldering  fluid,  drop  small  zinc  strips 
into  i  oz.  of  muriatic  acid  until  the  bubbles  cease 
to  rise,  then  add  #  teaspoonful  of  sal  ammoniac. 


COLD  STORAGE  TEMPERATURES 


ARTICLES. 

0  Fahr. 

ARTICLES. 

«Fahr. 

FRUITS. 

Apples                             

32-3^ 

CANNED  GOODS. 
Sardines  . 

35_40 

Hun  an  as      

!M 

Fruits  (Nuts  in  shell) 

35-40 

36 

Meats            * 

35  40 

Cranberries  

33-36 

Cantaloupes  

40 

Dates   Figs  etc 

50-55 

BUTTER   EGGS,  ETC 

Fruits  dried  

35-40 

Grapes  

34-36 

18  20 

Lemons                 

33  36 

Oranges  

34-36 

Eggs  

31 

Peaches  
Pears,  Watermelons  . 

MEATS. 
Brined  

34  36  | 
34-36 

38 

LIQUIDS. 
Beer,  Ale,  Porter,  etc. 
Cider 

33 

30 

Beef,  fresh  

33 

36 

Beef,  dried  

36-40 

Wines 

40  45 

Calves    

32-33 

Hams,  Bibs,  Shoulders 
(not  brined)      ..  . 

20 

Hogs  

29-32 

FLOUR  AND  MEAL. 

Lard 

38 

Buckwheat,  —  \\rheat 

Livers     

20-30 

Flour  

36  40 

Sheep,  Lambs  

32 

Corn  Meal  ,  Oats  

36-40 

Ox-tails 

30 

Sausage  Casings    
Tenderloins,  Butts,etc. 

VEGETABLES. 

20 
33 

MISCELLANEOUS. 
Furs,  Woolens,  Cigars, 
etc 

35 

Asparagus,  Carrots  .  .  . 
Cabbage,  Celery  

34-35 
34-35 
36-^40 

Honey,  Maple  Syrup, 
Sugar  

40-45 

Dried     Beans,     Corn, 

Hops  
Oils  

40 
35 

Onions,  Parsnips  

FISH. 
Fresh  Fish 

34-35 
20 

Poultry,  dressed,  iced. 
,,        dry  picked... 
„        scalded  
Game  —  Poultry  —  to 
freeze 

28-30 
26-28 
20 

15  18 

Dried  Fish  

36 

Game  after  frozen 

25-28 

Oysters  in  shell  

30-35 

Oysters  in  tubs  

25 

206 


BYE    PASS    VALVE 
AMMONIA  VALVES  AND    FITTINGS 

i.     Expansion  valve. 


207 


2.  Ninety-degree  angle 

valve. 

3.  Cross  valve. 

4.  Return  bend. 

5.  Ammonia  tank 

valve. 

6.  Forty-five-degree 

angle  valve. 

7.  Coupling. 

8.  Joint  cross. 

9.  Liquid  valve. 

10.  Ninety -degree  angle 

purger  valve. 

11.  Union  loop. 


BYE  PASS  VALVE  ON  THE  DOUBLE 
AMMONIA  GAS  PUMP 

Through  the  bye  pass  the  ammonia  can  be 
readily  exhausted  from  any  part  of  the  system  and 
may  be  stored  in  any  other  part  temporarily  until 
the  repairs  or  examinations  are  made. 

By  the  peculiar  arrangement  of  pipes  and 
valves  the  action  of  the  compressor  and  pump  can 


208 


BYE    PASS    VALVE 


be  reversed  and  the  gas  pumped   from  the  con- 
denser, storing  it  in  the  brine  tank. 

In  each  case,  after  the  examination  of  any 
part,  the  air  can  be  exhausted  therefrom  and 
charge  of  ammonia  reintroduced  without  the 
admixture  of  air. 


Ammonia 


Blinder 


Ammonia 

A.  B,  Ammonia  Pumps. 
Ai,   A2,     Discharge    Stop 

Valves. 

Bi,B2,  Suction  Stop  Valres. 
T>  2,   3.   4,  5,   6,   Bye  Pass 

Valves. 


M,    D,     Main    Discharge 

Pipe 
M,  S,  Main  Suction  Pipe. 


7,  8,  9,  Bye  Pass  Pipes. 
10,  Plunger  Valve. 

DESCRIPTION:  A,  B,  compressor  pumps;  Ai, 
A2,  main  discharge  stop-valves;  Bi,  B2,  main 
suction  stop-valves;  i  ,  2,  3,  4,  5,  6,  bye  pass 
valves;  M,  D,  main  discharge  pipe;  M,  S,  main 
suction  pipe;  7,  8,  Q,  bye  pass  pipes. 

How  TO  OPERATE:     To  exhaust  gas  from  pump 


BYE    PASS    VALVE  209 

^  all  bye  pass  valves  should  be  closed  to  begi  a 
with;  close  main  stop-valve  Bi,  B2  and  Aa;  open 
bye  pass  valves  2  and  3 ;  then  by  running  pump 
slowly  the  contents  of  pump  B  can  be  exhausted ; 
then  close  valve  4  and  remove"  bonnet.  After 
closing  bonnet,  air  can  be  removed  in  same  way, 
previously  shutting  main  stop-valve  Ai  and  ex- 
pelling the  air  through  purging  valve  on  pump- 
head;  close  all  bye  pass  valves  when  done  and 
open  main  stop-valve. 

To  EXHAUST  PUMP  A — Proceed  in  same  manner, 
using  the  opposite  set  of  valves. 

To  EQUALIZE  PRESSURE  between  condenser  and 
brine  tanks — Open  stop-valve  Ai  or  A2  and  bye 
pass  valves  i  and  2,  also  5  and  6,  thus  forming 
passage  direct  from  main  discharge  to  main 
suction  pipe. 

To  EXHAUST  CONDENSER  and  store  gas  in  brine 
tank — All  valves  closed  to  begin  with.  Open 
stop-valve  Ai  on  pump  A,  bye  pass  valves  i  and 
4,  opening  communication  to  pump  suction  B; 
expel  gas  by  opening  bye  pass  valves  2  and  5, 
thus  discharging  into  main  suction  pipe,  kun 
pumps  slowly  by  using  opposite  set  of  valves 
(either  pump  may  be  used),  the  mode  of  operation 
being  simply  that  one  pump  is  used  to  exhaust 
the  gas  through  the  bye  pass  from  the  discharge; 
while  the  other  forces  it  through  the  other  naif  oC 
bye  pass  into  the  suction  pipe. 


BOILING  POINT  OF  AMMONIA 


PRESSURE. 

S  Boiling  Point 
0  Fahr. 

Latent  Heat. 

PRESSURE. 

Boiling  Point 

Latent  Heat. 

K-» 

'os  Absolute. 

«o 

O 
—4.01 

Absolute. 

0) 

SB 
1 
43.30 

579.7 

58.00 

28.9 

537.6 

11.00 

—3.70 

—39 

579.1 

59.41 

44.71 

30.0 

536.9 

12.31 

—2.39 

—35 

576.7 

60.00 

45.30 

30.6 

536.5 

13.00 

—1.70 

-32.7 

575.3 

61.50 

46.80 

32.0 

535.7 

14.13 

—0.57 

—30 

573.7 

62.00 

47.30 

32.3 

535.5 

14.70 

4J3.00 

—28.5 

572.3 

63.00 

48.30 

33.0 

535.0 

15.00 

-J-0.30 

-27.8 

571.7 

64.00 

49.30 

33.7 

534.6 

16.17 

1.47 

—25 

570.7 

65.93 

51.23 

35.0 

533.8 

16.71 

2.01 

—22 

568.9 

67.00 

52.30 

35.8 

533.3 

17.00 

2.30 

—21.8 

568.7 

69.00 

54.30 

37.2 

532.4 

18.45 

3.75 

—20 

567.7 

71.00 

56.30 

38.6 

531.5 

19.00 

4.30 

—18.9 

567.0 

73.00 

58.30 

40.0 

530.6 

20.99 

6.29 

-15 

564.6 

74.07 

59.37 

41.0 

530.0 

JJ.27 

6.57 

—13 

563.4 

75.00 

60.30 

41.5 

529.7 

22.10 

7.40 

—12 

562.8 

76.00 

61.30 

42.2 

529.2 

J2.93 

8.23 

—11 

562.2 

78.00 

63.30 

43.4 

528.5 

23.77 

9.07 

—10 

561.6 

80.66 

65.96 

45.0 

527.5 

24.56 

9.86 

—  9 

561.0 

88.96 

74.26 

50.0 

524.3 

25.32 

10.62 

—  8 

560.4 

92.00 

77.30 

51.4 

523.4 

20.08 

11.38 

—  7 

559.8 

95.00 

80.30 

53.2 

522.3 

26.84 

12.14 

—  6 

559.2 

97.93 

83.23 

55.0 

521.1 

27.57 

12.87 

—  5 

558.5 

100.00 

85.30 

56.1 

520.4 

28.09 

13.39 

—  4 

557.9 

104.84 

90.14 

59.0 

518.6 

28.64 

13.94 

—  3 

557.3    1 

107.60 

92.90 

60.0 

517.9 

29.17 

14.47 

—  2 

556.7 

110.00 

95.30 

61.1 

517.2 

29.70 

15.06 

—  1 

556.1 

115.00 

100.30 

63.5 

515.7 

30.37 

15.67 

Hh  0  zero) 

555.5 

118.03 

103.33 

65.0 

515.3 

31.00 

16.30 

-J-1.4 

554.6 

119.70 

105.00 

66.0 

514.8 

A  FEW  TESTS  FOR  AMMONIA 

Ammonia  liquid  for  use  in  refrigerating  machines 
should  be  absolutely  pure.  It*  should  be  tested. 
The  various  tests  to  which  it  should  be  subjected 
are:  For  water,  for  specific  gravity,  for  inflam- 
mable gases,  and  for  boiling  point. 

TEST   FOR  WATER 

As  shown  in  the  engraving,  screw  into  the 
ammonia  flask  a  piece  of  bent  ^4-inch  pipe, 
which  will  allow  a  small  bottle  to  be  placed  so  as 

CLASSTUBE 

'JOBBER  I 


to  receive  the  discharge  from  it.  This  test  bottle 
should  be  of  thin  glass  with  wide  neck,  so  that 
quarter-inch  pipe  can  pass  readily  into  it,  and  of 
about  200  cubic  centimeters  capacity — equals  1.69 
gills  or  a  6%  ounce  bottle.  Put  the  wrench  on  the 
valve  and  tap  it  gently  with  a  hammer.  Fill  the 

bottle  about  one-third  full  and  throw  sample  out 
tti 


212  AMMONIA    TESTS 

in  order  to  purge  (clean)  valve,  pipe  and  bottle. 
Quickly  wipe  off  the  moisture  that  has  accumu- 
lated on  the  pipe,  replace  the  bottle  and  open 
valve  gently,  filling  it  about  half-full.  This  last 
operation  should  not  occupy  more  than  one 
minute.  Remove  the  bottle  at  once  and  insert  in 
its  neck  a  stopper  with  a  vent  hole  for  the  escape 
of  the  gas.  A  rubber  stopper  with  a  glass  tube 
is  the  best,  but  a  rough  wooden  stopper  loosely 
put  in  will  answer  the  purpose.  Procure  a  piece 
of  solid  iron  that  should  not  weigh  less  than  8 
Ibs. ,  pour  a  little  water  on  this  and  place  the  bottle 
on  the  wet  place.  The  ammonia  will  at  once 
begin  to  boil  and  in  warm  weather  will  soon 
evaporate.  If  any  residuum,  pour  it  out  gently, 
counting  the  drops  carefully.  Sixteen  drops  are 
about  equal  to  one  cubic  centimeter,  and  if  the 
sample  taken  amounted  to  100  cubic  centimeters, 
sixteen  drops  of  residuum  shows  one  per  cent 
impurities  (adulteration),  and  20  drops  i#  per 
cent. 

Care  is  necessary  in  the  drawing  of  the  sample, 
as  a  very  little  moisture  in  the  bottle,  or  in  the 
pipe,  or  a  brief  exposure  to  the  atmosphere  will  at 
once  affect  its  purity. 

TEST   FOR   SPECIFIC  GRAVITY 

The  specific  gravities  of  aqua  ammonia  by  the 
Beaume  scale  are  given  in  the  following  table. 


AMMONIA    TESTS 


213 


By  drawing  off  some  of  the  liquid  in  the  tall  test 
tube  generally  provided  by  ice-machine  builders, 
the  Beaume  hydrometer  may  be  inserted  and  the 
specific  gravity  read  upon  the  scale.  If  water  is 
present,  the  liquid  will  show  a  density  pro- 
portionate to  the  percentage  of  water  present. 

TABLE   OF    SPECIFIC   GRAVITIES   AND    PERCENTAGE 
OF    AMMONIA    (CARIUS) 


Degrees 

Specific 

Percent- 

Degrees 

Specific 

Percent- 

Beaume. 

Gravity. 

age. 

Beaume.. 

Gravity. 

age. 

10 

1.000 

0. 

21 

.9271 

19.4 

11 

.9929 

1.8 

22 

.921 

21.4 

12 

.9859 

3.3 

23 

.915 

23.4 

13 

.979 

5. 

24 

.909 

25.3 

14 

.9722 

6.7     . 

25 

.9032 

27.7 

15 

.9655 

8.4 

26* 

.8974 

30.1 

16 

.9589 

10. 

27 

.8917 

32.5 

17 

.9523 

11.9 

28 

.886 

35.2 

18 

.9459 

13.7 

29 

.8805 

19 

.9395 

15.5 

30 

.875 

20 

.9333 

17.4 

*  Called  by  the  trade  29}£  per  cent. 

Specific  Gravity  of  pure  anhydrous  ammonia  is  .623 

TEST   FOR   INFLAMMABLE   GASES 

Take  a  pail  of  water,  submerge  the  bent  pipe 
therein,  open  the  valve  on  flask  slightly  and  allow 
a  small  quantity  of  gas  to  flow  into  the  water.  If 
inflammable  gases  are  present  they  will  rise  in 
bubbles  to  the  surface  of  the  water  and  may  be 
removed  by  igniting  the  bubbles  by  means  of  a 
lighted  match  or  candle.  As  water  has  a  strong 
affinity  for  ammonia  it  will  be  readily  absorbed, 


214  TESTING    REFRIGERATING    MACHINERY 

while  air  or  other  gases  will  show  only  in  the  form 
of  bubbles. 

TEST   FOR     BOILING   POINT    OF    ANHYDROUS   AMMONIA 

By  inserting  the  special  low  temperature  stand- 
ardized chemical  thermometer  into  liquid  drawn 
into  the  6^  oz.  test  glass  jar,  readings  can  be 
obtained  through  the  side  of  the  jar  without 
removing  the  instrument.  Hold  the  thermometer 
in  such  a  position  that  only  the  bulb  is  immersed. 

This  test  will  give  you  the  boiling  point  of 
ammonia  at  atmospheric  pressure  and  it  is  well 
to  know  that  the  state  of  the  barometer  affects 
the  temperature  of  the  boiling  point.  With  the 
barometer  at  29.92  inches  the  boiling  point  should 
not  be  above  28.6  deg.  below  zero  and  may  be 
much  lower,  depending  upon  purity  of  sample.  If 
the  ammonia  is  impure  the  boiling  point,  is  raised 
in  proportion. 

TESTING  THE  REFRIGERATING 
MACHINERY 

PRESSURE  TEST. — It  is  important  before  introduc- 
ing the  charge  of  gas  into  the  machine  system  to 
carefully  test  every  part  of  the  apparatus  and  make 
it  thoroughly  tight  under  at  least  300  Ibs.  air  pres- 
sure, which  pressure  may  be  obtained  by  working 
the  ammonia  compressor  (pump)  and  allowing 
free  air  to  flow  into  suction  side  of  pump  by  open- 
ing special  valves  generally  provided  for  the 


TESTING    REFRIGERATING    MACHINERY          215 

purpose,  the  entire  system  being  thus  filled  with 
compressed  air  at  the  desired  pressure. 

While  this  pressure  is  being  maintained  a  search 
is  instituted  for  leaks,  every  pipe,  joint  and  square 
inch  of  surface  being  scrupulously  noted.  One 
method  is  to  cover  all  surfaces  with  a  thick  lather 
of  soap,  leaks  showing  themselves  by  formation  ' 
of  soap  bubbles.  In  the  case  of  condenser  and 
brine  tank  coils,  the  tanks  are  allowed  to  fill  with 
water,  the  bubbles  of  air  escaping  through  the 
water  locating  the  leak. 

It  is  important  that  the  apparatus  be  thoroughly 
tig  it,  and,  as  a  few  joints  are  to  be  made  when 
new  plants  are  put  in,  it  is  necessary  to  go  over 
the  entire  surface  of  the  system  to  be  sure. 

While  the  machine  is  engaged  in  pumping  air 
into  the  system  advantage  should  always  be  taken 
of  this  opportunity  to  purge  (clean)  the  system  of 
all  dirt  and  moisture.  To  do  this  properly, 
valves  are  provided  so  the  apparatus  may  be 
blown  out  by  sections,  removing  valve  covers 
(bonnets),  loosening  joints  for  this  purpose,  so 
that  it  is  positively  known  that  each  pipe,  valve 
and  space  is  strictly  clean  and  purged  of  all  dirt 
and  traces  of  moisture. 

A  final  test  may  then  be  had  by  pumping  air 
pressure  of  300  Ibs.  into  the  entire  system  and 
allowing  the  apparatus  to  stand  for  some  hours, 
estimating  the  leakage,  if  any,  by  noting  the 


2l6  TESTING    REFRIGERATING    MACHINERY 

degrees  of  pressure  as  shown  by  the  pressure 
gauge  connected  to  system.  The  air  pressure  will 
shrink  somewhat  at  first,  by  reason  of  losing  heat 
gained  during  compression  by  the  pumps.  As 
soon  as  the  air  parts  with  its  heat  and  returns  to 
its  normal  temperature,  the  gauge  will  come  to  a 
standstill  and  remain  at  a  fixed  point  (depending 
upon  the  barometer  and  upon  the  temperature  of 
the  room),  if  the  system  is  tight.  Never  charge  a 
system  until  it  is  well  cleansed,  purged  and 
absolutely  tight. 

VACUUM   TEST 

After  having  tested  the  system  with  a  pressure 
of  300  Ibs.  of  compressed  air,  the  air  must  be 
exhausted  from  the  entire  system,  by  working  the 
pumps  and  discharging  the  air  through  valves 
provided  therefor  (located  generally  on  the  pump 
domes).  When  the  escape  of  air  ceases  and  the 
compound  or  vacuum  gauges  show  a  full  vacuum, 
it  is  well  to  close  all  outlets  and  allow  the 
machinery  and  system  to  stand  for  some  time,  to 
test  the  capacity  of  the  apparatus  to  withstand 
external  pressure  without  leakage.  In  some  cases 
it  has  been  discovered  that  parts  while  tight  from 
internal  pressure,  owing  to  loose  particles  lodging 
over  leaks  and  acting  as  plugs  to  prevent  escape, 
give  way  and  disclose  the  leakage  when  sub- 
jected to  an  external  pressure. 


INTRODUCING  THE  CHARGE  OF 
AMMONIA 

Place  the  ammonia  flask  (tatok)  on  small  plat 
form  scales,  in  order  to  weigh  the  contents  and 
know  positively  when  flask  is  exhausted.  Con- 
nect the  flask  to  the  charging  valve,  the  gauge 
still  showing  a  vacuum,  close  the  expansion  valve 
in  main  liquid  pipe  connecting  receiver  to  brine 
tanks;  then  open  valve  on  ammonia  flask  and 
allow  the  liquid  to  be  exhausted  into  the  system. 

The  machinery  may  be  run  all  this  time  at  a 
slow  speed,  with  both  discharge  and  suction  hand 
stop  valves  wide  open. 

As  one  flask  is  exhausted,  place  another  on  the 
scales  and  continue  until  the  liquid  receiver  is 
shown  to  be  partly  full  by  the  glass  gauge  thereof. 
Then  shut  the  charging  valve  and  open  and 
regulate  the  main  expansion  valve.  The  machine 
is  then  sufficiently  charged  to  do  work,  as  shown 
by  the  pressure  gauges  and  gradual  cooling  of  the 
brine  and  frosting  of  expansion  pipe  leading  to 
brine  tank  coils. 

While  the  system  is  being  charged  water  is 
allowed  to  flow  on  the  condenser,  and  time  dili- 
gently employed  in  searching  further  for  leaks, 
which  can  readily  be  detected  by  sense  of  smell, 
^ach  joint  being  again  gone  over. 


2l8  QUESTIONS    AND    ANSWERS 

Q. — Why  are  the  joints  and  whole  system  again 
gone  over  after  having  withstood  the  two  tests, 
300  Ibs.  air  pressure  and  lowest  vacuum? 

A. — Because  ammonia  in  itself  is  a  great  dis- 
solvent and  eventually  it  will  purge  and  scour  the 
entire  system  clean  to  the  metal  surfaces. 

Q.— Where  does  the  loose  foreign  matter  go? 

A. — It  is  caught  in  the  separators  and  inter- 
cepters  provided  for  this  purpose. 

Q. — Is  ammonia  a  lubricant? 

A.— Yes,  slightly. 

Q. — Has  it  any  effect  on  iron  or  steel? 

A. — None  whatever. 

Q. — Has  it  any  effect  on  brass,  copper,  etc.? 

A. — Yes,  it  eats  and  corrodes  them. 

AIR  IN  THE  SYSTEM 

Q.— What  causes  air  to  get  in  the  system? 

A. — Negligence  in  regulating  the  expansion 
valve,  needlessly  pumping  a  vacuum  on  the  brine 
tank,  leaky  piston  rods,  also  taking  the  apparatus 
apart  and  not  expelling  the  air  before  the  re- 
introduction  of  the  anhydrous  ammonia  gas. 

Q. — How  is  the  pressure  of  air  in  system  in  con- 
siderable quantity  readily  noticed? 

A. — By  the  intermittent  action  of  the  expansion 
valve  and  singing  noise,  rise  of  condensing  pres- 
sure, loss  of  efficiency  in  the  condenser,  etc. 

Q. — What  means  are  provided  for  the  escape  of 


DISCHARGING    AMMONIA  219 

the  imprisoned  air  to  restore  the  apparatus  to  its 
normal  condition  of  pressure  and  efficiency? 

A. — The  purging  (cleaning)  valves  on  the  con- 
denser or  the  bye  pass.  (See  description  of  bye 
pass  on  pumps,  pages  208  and  20*9. ) 

TAKING  THE  AMMONIA  OUT  OF  THE  APPARATUS 

Q.— How  can  ammonia  be  taken  out  of  the  sys- 
tem of  an  ice  machine  without  losing  any  of  it? 

A. — If  the  plant  is  of  ordinary  construction  and 
of  compression  (liquefying  gas  by  gas  pump) 
design,  connect  the  liquid  receiver  by  its  bottom 
connection  to  the  empty  shipping  tank  and 
allow  the  gas  to  flow  into  the  tank,  being  sure  to 
have  ^the  tank  on  a  scale  to  weigh  the  quantity 
you  put  in. 

Do  not  allow  more  to  be  placed  in  the  tank  than 
was  originally  in  it  when  shipped.  In  other 
words,  the  tank  must  not  be  filled  with  liquid  to 
more  than  five-eighths  of  its  cubic  contents. 

This  is  one  of  the  most  dangerous  pieces  of 
work  that  a  refrigerating  engineer  is  called  on  to 
do,  and  on  the  first  trial  the  chances  are  ,about 
even  that  he  will  burst  the  compressor,  blow  the 
receiving  tank  up  and  possibly  blow  his  own  head 
off. 

QUESTIONS  AND  ANSWERS  IN   REVIEW 

Q. — How  is  the  compressor  pump  cylinder  kept 
cool? 
A. — It  is  incased  with  a  water  jacket  through 


220  QUESTIONS   AND   ANSWERS 

which  cold  water  is  constantly  circulated  (see  J, 
Fig.  2,  page  199). 

Q. — What  causes  the  heat  in  the  pump? 

A. — The  compression  of  the  gas. 

Q.  — What  kind  of  oil  should  be  used  in  the  com- 
pressor, if  used  at  all?  % 

A. — Oil  generally  known  as  "the  perfection 
ammonia  pump  oil,"  or  the  cold  test  "zero  oil," 
which  is  especially  manufactured,  and  which 
stands  a  very  low  degree  of  cold  without  volatiliz- 
ing. Sometimes  the  best  paraffine  oil  is  used, 
and  again  a  clear  West  Virginia  crude  oil.  These 
oils  when  subjected  to  a  low  temperature  should 
not  freeze. 

Never  inject  oil  directly  into  the  compressor, 
and  use  sparingly  in  the  stuffing  box. 

Q. — What  is  an  oil  separator  used  for? 

A. — It  is  to  eliminate  the  small  quantity  of  oil 
from  the  ammonia  gas  in  its  passage  from  the 
compressor  to  the  condenser. 

Q. — Is  the  ammonia  gas,  when  exhausted,  in- 
flammable? 

A. — Yes,  sometimes,  if  the  oil  traps  have  not 
absorbed  the  oil  which  the  gas  carries  off  from  the 
hot  pump. 

Q. — Is  ammonia  dangerous  to  handle? 

A. — It  is,  because  when  condensed  to  a  liquid 
it  is  under  an  enormous  pressure,  which  may 
cause  great  destruction  when  suddenly  released. 


IN    REVIEW  221 

Q. — What  advantage  has  the  bye  pass  valve? 

A. — By  means  of  it  the  ammonia  can  be  ex- 
hausted from  any  part  of  the  machine  that  may 
need  repairing. 

Q. — What  is  an  ammonia  receiver,  and  where 
is  it  placed? 

A. — It  is  a  tank  to  store  liquefied  ammonia, 
and  is  placed  between  the  condenser  and  expan- 
sion valve  (see  condenser). 

Q. — What  do  the  pipes  in  a  cold  storage  room 
with  a  very  low  temperature  contain? 

A. — They  contain  ammonia  gas. 

Q. — What  do  the  pipes  used  in  a  hotel  for  cool- 
ing living  rooms  contain? 

A. — They  contain  brine. 

Q.— What  does  a  gas  need  for  expansion  and 
how  does  it  get  what  it  needs? 

A. — It  needs  heat  and  takes  it  from  the  sur- 
roundings. 

Q. — But  what,  if  the  surroundings  have  no 
heat? 

A. — Heat  means  any  degree  of  temperature. 
Taking  heat  from  surroundings  means  lowering 
their  temperature.  Taking  heat  from  cold  sur- 
roundings means  making  them  still  colder. 

Q.  — In  which  three  forms  does  matter  exist? 

A.  — Solid,  liquid  and  gaseous. 

Q. — Does  iron  exist  in  these  three  forms? 

A. — We  can  liquefy  it   by  melting  it  in  great 


222  QUESTIONS    AND    ANSWERS 

heat,  and  it  is  affirmed  that  iron  exists  in  gaseous 
form  in  the  sun. 

Q. — How  can  this  be  known? 

A. — "Spectral  analysis"  reveals  the  fact 

Q. — Why  does  ice  float? 

A. — Because  ice  is  lighter  than  water  at  any 
temperature. 

Q._What  makes  it  lighter? 

A. — Expansion.  A  pound  of  ice  has  more 
volume  than  a  pound  of  water. 

Q. — Whst  would  happen,  if  ice  were  denser  and 
therefore  heavier  than  water  at  any  temperature? 

A. — In  severe  winters  the  deepest  lakes  would 
freeze  solid  down  to  the  bottom. 

Q. — Does  ice  keep  on  expanding,  the  colder  it 
grows? 

A.— No,  there  is  a  point  at  which  it  begins  to 
contract  again. 

Q. — Why  does  it  not  keep  the  same  volume? 

A. — Because  change  of  temperature  is  impos- 
sible without  change  of  volume. 

Q. — Is  that  a  law  of  nature? 

A.  — It  is  a  truth  established  by  sufficient  obser- 
vation, that  one  never  occurs  without  the  other. 


A   STEAM   AND   WATER-PIPE   CEMENT 

that  will  set  under  water,  is  made  of  2  Ibs.  ground 
Paris  white,  5  Ibs.  ground  lithage,  X  lb.  fine  yel- 
low ochre,  ^4  °z-  hemp  cut  up  small.  Mix  well 
with  linseed  oil  to  the  consistence  of  putty  ,and  use 
at  once. 


LIQUID  AIR,  THE  COMING  FORCE 

Water  freezes  at  32°  above  zero.  Mercury  in  a 
thermometer  freezes  solid  at  40-42°  below  zero. 
The  alcohol  in  a  spirit  thermometer  freezes  at  200 
below.  Air  becomes  a  liquid  at  312°  below  zero. 

Eight  hundred  cubic  feet  of  free  air  are  con- 
densed into  one  cubic  foot  of  liquid  air.  One  pint 
of  liquid  air  weighs  one  pound,  like  water. 

By  the  aid  of  a  so-horse-power  steam  air  pump 
ordinary  air  is  compressed  until  it  becomes  red- 
hot.  **  Then  it  is  cooled  in  submerged  pipes,  and 
is  further  compressed  until  the  pressure  is  regis- 
tered at  thousands  of  pounds  to  the  square  inch. 
More  cooling  is  done,  and  more  pressure  applied, 
until,  finally,  the  air  liquefies.  It  oozes  through 
the  steel  of  the  pipe  in  the  shape  of  a  milky  vapor 
and  trickles  down  into  the  receptacle  below. 

As  there  is  a  difference  of  344°  between  the 
temperatures  of  ice  and  liquid  air,  it  will  be  under- 
stood why  liquid  air  boils  furiously  even  when 
placed  on  a  block  of  ice. 

A  hand  thrust  into  this  liquid,  in  appearance 
like  water,  would  be  destroyed  in  10  seconds,  but 
if  drawn  out  again  instantly,  the  moisture  of  the 
skin  freezing  to  ice  would  be  protection  enough. 
The  feeling  at  touching  the  liquid  is  like  that 
of  iron  at  white  heat. 

223 


224       LIQUID    AIR,    THE    COMING    FORCE 

Like  quicksilver,  liquid  air  does  not  adhere.  If 
poured  over  silk,  it  will  leave  no  stain. 

When  boiling,  the  vapor  of  liquid  air,  being 
nothing  but  highly-compressed  air,  sinks  to  the 
ground. 

If  water  is  poured  into  liquid  air  it  turns  to  ice 
instantly,  and  of  such  a  low  temperature  that  it 
will  not  melt  near  a  red-hot  stove  for  a  long  time. 

A  stick  of  arc  light  carbon,  heated  to  2,000 
degrees  above  zero,  thrust  into  liquid  air,  causes  the 
oxygen  in  it  to  burn  with  a  dazzling  bright  flame. 

A  teaspoonful  of  liquid  air  in  a  closed  vessel,  if 
lighted,  explodes  with  tremendous  force,  jarring 
the  ground  like  an  earthquake. 

The  expansive  power  of  liquid  air  is  about  20 
times  greater  than  that  of  steam. 

Ten  years  ago  it  cost  about  $2,000  to  produce  i 
gallon  of  liquid  air.  To-day,  so  Prof.  Chas.  E. 
Tripler,  of  New  York,  states,  it  can  be  manu- 
factured at  the  cost  of  3  or  4  cents  a  gallon,  at  the 
rate  of  40  or  50  gallons  a  day. 

Some  of  the  uses  to  which  this  uncanny  sub- 
stance can  be  put  are  as  follows: 

A  steam  engine  horse-power  is  now  figured  at 
$36.00  a  year  expense ;  by  the  use  of  liquid  air  it 
should  not  be  more  than  about  $7.00. 

The  resistance  in  electric  wires  is  entirely  over- 
come, if  submerged  in  liquid  air.  The  intense 
cold  knits  the  molecules  of  metal  so  closely  that 


LIQUID    AIR    AND    HYDROGEN  225 

it  becomes  a  perfect  conductor,  without  any 
leakage. 

A  pocket  flask  full  of  liquid  air  will  furnish  free 
air  for  submarine  apparatus  for  hours. 

It  furnishes  a  clean,  dry  cold,  at  any  desired 
temperature,  for  refrigerators,  hospitals,  engine 
rooms,  etc. 

If  used  in  propelling  steamships,  there  would  be 
no  heat  in  the  furnace  room,  and  little  need  of  a 
furnace. 

Guns  using  liquid  air  as  an  explosive  would 
never  get  hot. 

Liquid  air  sprayed  on  dangerous  wounds  arrests 
blood  poisoning  instantly,  as  by  a  miracle.  Malig- 
nant cancers  have  been  cured  by  one  drop  of  the 
liquid.  All  pulmonary  and  throat  diseases,  hay 
fever,  asthma,  diphtheria,  grip  and  all  fevers 
yield  to  a  spray  of  liquid  air. 

LIQUID   HYDROGEN 

In  the  spring  of  1898,  Prof.  Dewar,  of  the  British 
Royal  Institution,  succeeded  in  liquefying  the 
most  volatile  of  all  gases,  hydrogen.  Liquid 
hydrogen  is  colorless,  transparent,  and  of  only 
one-fourteenth  of  the  density  of  water.  It  is  so 
cold  that  it  freezes  and  solidifies  air  and  oxygen 
instantly.  In  a  closed  tube  brought  in  contact 
with  it,  the  air  freezes  into  a  small  lump,  leaving 
the  tube  a  vacuum. 


226 


THE   MACHINE    SHOP 


TOOLS 


227 


THE  MACHINE  SHOP 

One  of  the  things  by  which  a  mechanic  is 
known,  is  the  way  he  keeps  his  tools.  It  makes 
no  difference  whether  he  works  in  a  small  shop  or 
in  one  of  the  great  establishments,  every 
mechanic  should  be  inflexible  in  following  these 

TWO  RULES: 

1.  Every  tool  should  have  its  exact  place,  and 
should  be  in  that  place  when  not  in  actual  use. 

2.  Every  tool  should  be  in  good  order  and  ready 
for  use. 

A  mechanic  with  whom  the  constant  observation 
of  these  rules  has  grown  to^  be  a  habit,  is  worth 
three  others  to  his  employer,  and  saves  himself  a 
great  amount  of  annoyance,  loss  and  worry. 

LATHE  GEARING 


To  gear  a  lathe  to  cut  any  number  of  threads 
when  no  gear  plate  is  attached  to  lathe  bead 


art 


THE    MACHINE    SHOP  229 

block,  simply  find  the  run  of  gears  belonging 
to  the  lathe  to  know  if  odd  or  even  number  of 
teeth  are  on  gears. 

Multiply  the  number  of  threads  to  be  cut  to  the 
inch  by  any  small  number  from  3  up  to  6  that  will 
bring  the  answer  even  with  one  of  the  gears  on 
hand.  Say  10  threads  are  to  be  cut — 4  times  10 
equals  40.  Place  this  gear  on  lead  screw  of  lathe. 
Multiply  the  same  number  (4)  by  the  number  of 
threads  per  inch  on  your  lead  screw,  say  6.  6x4= 
24.  Place  24  tooth  gear  on  spindle,  and  connect 
by  suitable  intermediate. 

TURNING  A   BALL 

There  are  expensive  machines  for  turning  balls, 
but  common  lathes  will  produce  perfect  spheres. 

Turn  the  piece  first  on  centers,  using  the 
calipers  to  get  it  approximately  near  the  shape; 
then  cut  off  the  centers. 

Make  a  cup  in  a  chuckblock  of  hardwood,  to 
hold  a  small  section  of  the  ball,  and  for  the 
center  use  a  blunt  wood  center  with  a  concave 
piece  of  copper.  Put  the  work  in.  the  chuclt  so 
as  to  take  the  first  cut  around  it  in  the  direction 
of  its  former  centers,  or  axis. 

Cut  lightly  and  a  very  narrow  ribbon  all 
around;  then  change  the  chuck  so  as  to  cut  the 
second  ribbon  at  right  angles  with  the  first,  with 
the  same  depth  of  cutting.  Then  the  third 


230 


THE    MACHINE    SHOP 
LATHE   TOOLS 


1.  Half  Diamond  Point. 

2.  Diamond    Point    for 

steer  and  iron,  left 
hand. 

3.  Diamond    Point    for 

steel  and  iron,  right 
hand. 

4.  Heavy      Diamond 

Point  for  Cast  Iron. 

5.  Right      Side      Tool, 

bent. 

6.  Left  Side  Tool,  bent. 

7.  Right  Side  Tool. 


8.  Left  Side  Tool. 

9.  Inside  Thread  Tool. 

10.  Inside  Turning  (Bor- 

ing) Tool. 

11.  Bent  Thread  Tool. 

12.  Thread        Tool, 

straight. 

13.  Roughing  Tool. 

14.  Cutting-off  Tool. 

15.  Water         Finishing 

Tool. 

16.  Round  Nose  Tool. 


NOTE:  Set  the  cutting  edge  a  little  above  the 
axis,  or  it  will  not  cut  properly,  and  may  be  drawn 
under  and  broken  off. 


TWIST    DRILL    GRINDING 


231 


ribbon  half-way  between  the  first  two,  and  so  on, 
until  the   whole   surface  is  covered.      The  right 
angle  need  not  be  measured  except  with  the  eye. 
Finish  the  ball  with  a  hand  tool,  or  scraper. 


TWIST  DRILL  GRINDING 

The  cutting  edges  of  a  drill  must  have  a 
proper  and  uniform  angle  with  the  longitudinal 
axis  of  the  drill  (Fig.  i);  the  two  edges  must  be 
straight  and  exactly  of  the  same  length ;  and 
the  lips  must  be  sufficiently  backed  off  (Fig.  6). 

Q.— What  is  the 
proper  angle  to 
which  a  drill  should 
be  ground? 

A. — 59  degrees. 
(See  Fig.  i.) 

Q.  —  What  is  the 
result  of  an  improper 
angle? 

A. — A  lesser  angle 
gives  a  longer  edge, 
likely  to  hook  and  to  produce  a  crooked  and  irregu- 
lar hole.  A  larger  angle  gives  too  short,  an  edge 
to  do  the  work  easily. 

Q. — Where  is  the  longitudinal  axis  of  the  drill? 

A. — It  is  at  the  intersection  of  the  two  longitu- 


Fig.  i 


232 


QUESTIONS    AND    ANSWERS 


dinal  planes  indicated  by  the  scribing  (center  line) 
along  the  middle  of  the  two  grooves. 

Q. — Of  what  importance  is  this  axis? 

A. — The  cutting  edges  must  be  at  equal  dis- 
tances from  it,  and  also  at  the  right  distance  to 
get  the  proper  angle  of  point. 

Q.— What  is  this  point? 

A. — It  is  the  part  where  the  two  edges  of  the 
lips  are  run  together  in  the  center.  If  the  cutting 
edges  are  too  far  from  the  axis  the  angle  point 
does  not  cut;  if  too  near,  it  cuts  too  rank. 


Fig.  2 


Fig.  3 


Fig.  4 


Fig.  5  Fig.  6 

Fig.  2  shows  the  proper  proportions.     In  Fig.  3 

the  edge  is  too  near  the  center  line,  and  in  Fig.  4 

it  is  too  far  from  it. 

Q. — What  is  clearance? 


THE    MACHINE   SHOP  233 

A. — The  amount  which  is  champered  off  back 
from  the  cutting  edge. 

Fig.  5  shows  how  the  clearance  is  determined 
as  well  as  the  height  of  the  cutting  lips,  which 
should  be  equal,  as  stated  before. 

Q.— What,  if  there  is  not  sufficient  clearance? 

A. — The  drill  will  not  cut,  and  under  force  wfli 
split  or  break.  Fig.  6  shows  the  rear  of  lip  removed. 

Q. — How  would  you  start  a  drill? 

A. — By  hand,  in  order  to  see  first  how  it  works. 
If  it  cuts  well,  the  chips  will  show  a  clean  cutting 
surface. 

Q. — Does  a  good  drill  in  the  ^  "line  cut  small 
chips? 

A. — In  cast  metal,  yes;  but  in  wrought  metal, 
it  will  cut  a  curled  shaving  sometimes  very  long. 

Q. — Why  are  the  two  grooves  shallower  near 
the  shank  than  near  the  point? 

A. — The  center  is  made ,  thicker  toward  the 
shank  for  strength.  As  the  drill  wears  short,  the 
center  must  be  thinned  out  by  grinding,  care 
being  taken  to  remove  an  equal  amount  of  stock 
on  each  side  and  so  keep  the  point  central.  * 

POLYGONAL  NUTS 

A    4  sided  nut  is  called  square. 
AS      "       "     "      "      a    Pentagon 
A     6      "       "     "      "       "     Hexagon. 
A     7      "       "     "      "       "     Heptagon. 
An  8      "       "     "      "       an  Octagon. 


RULES   AND  STANDARD  NUMBERS 


DIAMETER,  CIRCUMFERENCE  AND  AREA 

In  a  circle  of  one   inch  diameter   describe    16 
radii    at    equal  distances   (Fig.   i).     The  spaces 

FIG.  I. 


between  them  and  the  16  parts  of  the  circum- 
ference may  be  arranged  in  a  double  row  (Fig.  2). 

The  circle  area  is  thus  divided  up  into  16  parts, 
8  of  which  are  placed  in  nearly  a  straight  line  on 
each  side  of  the  row. 

By  actual  measurement  the  width  of  this  row  is 
%  inch  and  the  length  i.57o8/x  (allowing  a  trifle 
for  the  difference  between  the  8  little  curves  and 
a  straight  line). 


Therefore  cir- )  _o  v  1  WW 

cumference    f     ' 

Area  =1.5708"  X  Yz" 

Difference  of) 
areas  of  circle  V=  sum  of  4  corners  (Fig.  1) 

and  square     ) 


=  3.1416" 

=  0.7854  sq.  inch. 

=  0.2146  sq.  inch. 


RULES    AND    STANDARD    NUMBERS       235 


STANDARD    MULTIPLIERS 

1.  For    the   area  of   a   circle,    multiply 

square  of  diameter  by 7854 

2.  For  the  circumference  of  a  circle,  mul- 

tiply diameter  by 3. 1416 

3.  For  the  diameter  of  a  circle,  multiply 

circumference  by ,. 31831 

4.  For  the   surface  of  a  ball,  multiply 

square  of  diameter  by 3. 1416 

5.  For  the  cubic  inches  in  ball,  multiply 

cube  of  diameter  by 5236 

6.  For  the  cubic  contents  of  a  cylinder, 

multiply  the  area  by  the  length. 

7.  For  the  pressure  in  Ibs.  per  sq.  inch 

in  a  column  of  water,  multiply  its 
height  in  feet  by , 434 

AREA   OF   CIRCLES 


DlAM. 

AREA 

DlAM. 

AREA 

DlAM. 

AREA 

DlAM. 

AREA 

% 

0.6013 

13 

132.73 

36 

IOI7.8 

71 

3959-2 

I 

0.7854 

14 

153-93 

37 

1075.2 

72 

407L5 

# 

1.767 

I4# 

165.13 

4i 

1320.2 

76 

4536.4 

2 

3-I4I 

i6# 

205.97 

45 

1590.4 

80 

5026.5 

X 

3-976 

18 

254.46 

46 

1661.9 

81 

5153-0 

X 

4.908 

K 

268.80 

47 

1734-9 

82 

5281.0 

* 

5-939 

19 

283.52 

48 

1809.5 

83 

5410.6 

3 

7.068 

# 

298.64 

49 

1885.7 

.84 

5541-7 

X 

8.295 

20 

3I4-I6 

50 

1963.5 

85 

5674.5 

% 

9.621 

X 

330.06 

5i 

2042.  8 

86 

5808.8 

X 

11.044 

21 

346.  36 

52 

2123.7 

87 

5944-6 

4 

12.566 

tf 

363-05 

53 

2206.  I 

88 

6082.  i 

K 

15.904 

22 

380.13 

54 

2290.2 

89 

6221.1 

5 

I9-635 

V2 

397.60 

55 

2375-8 

90 

6361.7 

Q. — What  difference  is  there  between  3  square 
feet  and  3  feet  square? 


236  QUESTIONS    AND    ANSWERS 

A. — The  first  means  3  squares,  each  one  foot 
square;  the  second  is  9  squares,  each  one  foot 
square,  arranged  in  3  rows  of  3  squares  each. 

Q. — Is  there  any  difference  between  one  square 
foot  and  one  foot  square? 

A.— No. 


WEIGHTS  AND  MEASURES 

Q. — How  many  square  inches  in  a  square  foot? 

A. — 12  times  12,  or  144. 

Q. — How  many  cubic  inches  in  a  cubic  foot? 

A. — 12  times  12  times  12,  or  1728. 

Q. — How  many  cubic  inches  in  a  gallon,  in  a 
cubic  foot,  in  a  bushel? 

A. — 231  in  a  gallon;  1,728  in  a  cubic  foot;  2,150 
in  a  bushel. 

Q. — How  many  gallons  in  a  cubic  foot  of  water? 

A. — Tfa  gallons. 

Q. — How  many  cubic  inches  in  one  pound  of 
water  at  60°  F.? 

A. — 27.71  cubic  inches. 

Q. — How  do  you  figure  the  gallons  contained  in 
a  barrel? 

A. — Add  together  the  two  diameters  (in  inches) 
of  the  barrel  at  head  and  bung,  and  divide  the 
sum  by  2,  which  gives  the  mean  diameter.  Multi- 
ply the  square  of  this  diameter  by  .7854,  which 
gives  the  area  of  the  mean  diameter  circle  in  sq. 
inches.  Multiply  this  area  by  the  length  of  the 


WEIGHTS    AND    MEASURES  237 

barrel  in  inches,  to  get  the  cubic  contents  in  cubic 
inches,  and  divide  the  product  by  231  to  get  the 
gallons. 

Example:  A  barrel  40  inches  long,  19  inches 
diameter  at  the  head,  25  inches  diameter  at  the 
bung. 

19  +  25  =  44      44-f-2  =  22 

22  X  22  =  484     484  X  .7854  =  380 
380  X  40  =  15200    15200  -H  231  =  65.9  gall 

Q. — How  much  does  a  cubic  inch  of  water 
weigh? 

A. — It  weighs  .0361  of  a  pound,  or  .577  of  an 
ounce. 

Q. — What  is  the  weight  of  a  gallon,  a  cubic  foot 
of  water? 

A. — A  gallon  weighs  8^  Ibs.  K  a  cubic  foot  62 K 
Ibs. 

Q. — What  is  the  weight  of  a  column  of  water, 
one  inch  sq.  and  2.309  feet  high,  the  temperature 
at  60°  F.? 

A. — One  pound. 

Q. — What  is  the  weight  of  a  column  of  water, 
one  inch  sq.  and  one  foot  high? 

A. — It  weighs  .434  Ibs.  * 

Q. — How  much  does  a  cubic  inch  of  mercury 
weigh? 

A. — It  weighs  .49  of  a  pound. 

Q. — How  much  does  a  column  of  mercury  one 
inch  sq.  and  30  inches  high,  weigh? 

A. — 14.7  Ibs. 


238  QUESTIONS    AND    ANSWERS 

Q. — What  is  meant  by  a  miner's  inch? 

A. — It  is  approximately  equal  to  a  supply  of 
12  gallons  per  minute. 

Q. — In  what  relation  does  the  friction  of  water 
in  pipes  stand  to  the  velocity  of  flow? 

A.— It  increases  with  the  square  of  velocity. 
If  the  velocity  increases  4  times,  the  friction 
increases  16  times. 

Q. — In  what  relation  does  the  capacity  of  pipes 
stand  to  their  diameter? 

A. — It  increases  with  its  square.  Doubling  the 
diameter  increases  the  capacity  four  times. 

Q. — How  much  water  is  consumed  in  obtaining 
one  nominal  horse  power  in  heating  buildings,  etc.  ? 

A. — One  cubic  foot. 

Q. — How  much  for  engine  purposes? 

A. — One-half  cubic  foot. 

Q. — How  much  heating  surface  is  allowed  for 
one  nominal  H.  P.  in  boilers? 

A. — 15  sq.  feet  for  horizontal,  and  12  sq.  feet 
for  vertical. 

Q. — How  do  you  find  the  H.  P.  required  to 
elevate  water  to  a  given  height? 

A. — Multiply  the  total  weight  of  water  in  Ibs. 
with  the  height  in  feet  and  divide  the  product  by 
33,000.  Then  allow  25  per  cent  for  water  friction 
and  25  per  cent  for  steam  loss,  in  all  50  per  cent, 
or  one-half,  which  is  the  same  as  dividing  by 
16,500  instead  of  by  33,000. 


WEIGHTS    AND    MEASURES  239 

Q. — How  do  you  find  the  total  amount  of  pres- 
sure exerted  by  a  pump,  and  how  the  resistance? 

A. — The  area  of  the  sleam  piston,  multiplied 
by  the  steam  pressure,  gives  the  pressure.  The 
area  of  the  water  piston,  multiplied  by  the  water 
pressure  per  sq.  in. ,  gives  the  resistance. 

Q.— If  pressure  and  resistance'  are  the  same, 
does  the  pump  work? 

A.— No,  there  must  be  a  margin  of  from  30  to 
50  per  cent  steam  pressure  according  to  the  re- 
quired speed. 

PULLEY   SPEED    CALCULATION 

Driven  pulley  revolutions  are  found  by  multiply- 
ing the  diameter  of  the  driver  by  its  number  of 
revolutions  and  dividing  by  the  diameter  of  the 
driven. 

Diameter  of  driving  pulley  is  found  by  multiply- 
ing the  diameter  of  the  driven  by  the  number  of 
revolutions  it  shall  make  and  dividing  the  answer 
by  revolutions  of  driver  per  minute. 

Diameter  of  driven  pulley  that  should  make  a 
certain  number  of  revolutions  is  found  by  multiply- 
ing the  diameter  of  the  driver  by  its  number  of 
revolutions  and  dividing  [by  the  revolutions  the 
driven  should  make. 

SQUARE  ROOT 

Q. — How  is  the  square  root  of  a  number  found? 
A. — i  st— Separate  the  number   into  periods  of 


240  WEIGHTS    AND    MEASURES 

two  figures  each,  beginning  at  the  right  hand  or 
digit  space. 

2d  —  Find  the  greatest  number  whose  square  is 
contained  in  the  period  on  the  left;  this  will  be 
the  first  figure  in  the  root. 

3d  —  Subtract  the  square  of  this  figure  from  the 
period  on  the  left,  and  to  the  remainder  annex 
the  next  period  of  two  figures  to  form  a  dividend. 

4th  —  Divide  this  dividend,  leaving  out  the  last 
single  figure  on  the  right,  by  double  the  part  of 
root  already  found,  annex  the  answer  to  that  part 
and  also  to  the  divisor,  then  multiply  the  divisor 
thus  completed  by  the  figure  of  the  root  last 
obtained  and  subtract  the  product  from  the 
dividend. 

5th  —  If  there  are  any  more  periods  to  be  brought 
down  continue  the  operation  in  the  same  manner 
as  before. 

Note  —  If  a  cipher  occurs  in  the  root,  annex  a 
cipher  to  the  trial  divisor  and  another  to  the 
dividend,  and  proceed  as  before. 

EXAMPLES  : 

18,66,24  |  432  Sq.  Root.  .0,00,36  |  .006  Sq.  Root. 

16  0  * 

00  |  00 
249  00 


862  |  1724  006  |  0036 

1724  0036 


LEVERAGE 

Q.— Name  the  three  points  in,  a  lever. 

A. — Force,  weight  and  fulcrum. 

Q. — If  the  fulcrum  is  between  the  force  and 
weight,  what  kind  of  a  lever  would  it  be? 

A.— A  lever  of  the  first  kind. 

Q. — If  the  weight  is  between  the  force  and  the 
fulcrum,  what  kind  would  it  be? 

A. — A  lever  of  the  second  kind. 

Q. — When  the  force  is  between  the  weight  and 
the  fulcrum,  what  kind  would  it  be? 

A. — It  is  a  lever  of  the  third  kind. 

Q. — State  how  the  proportions  of  a  lever  of  the 
first  kind  are  found? 

A.— By  dividing  the  length  of  that  end  of  the 
lever  between  fulcrum  and  weight  into  the  length 
of  the  opposite  end.  Example:  If  length  of  lever 
between  fulcrum  and  weight  is  6  inches  and  the 
other  1 8  inches  the  lever  is  said  to  be  3  to  i,  and 
a  weight  equal  to  3  times  the  force  applied  at 
force  may  be  lifted  at  weight  by  pulling  down  at 
force. 

Q. — How  do  you  figure  the  lever  of  the  second 
kind? 

A.— By  dividing  the  length  of  the  end  of  lever 
between  the  fulcrum  and  weight  into  the  total 


242  USEFUL    KNOWLEDGE 

length  of  the  lever.  Example :  If  length  of  lever 
between  fulcrum  and  weight  is  6  inches  and  the 
other  24  inches  the  lever  is  said  to  be  4  to  i,  and 
a  weight  may  be  lifted  at  weight  equal  to  4  times 
the  force  applied. 

Q. — What  are  the  lever  proportions  of  third 
kind? 

A. — They  are  found  by  dividing  total  length  of 
lever  into  the  length  of  the  end  between  fulcrum 
and  force.  Example:  If  total  length  of  lever  is 
30  inches  and  the  length  between  weight  and  force 
24  inches,  the  lever  is  said  to  be  an  8-10  to  i,  and 
a  weight  equal  to  8-10  of  the  force  applied  at 
force  may  be  lifted  at  weight. 


GENERAL  USEFUL  KNOWLEDGE 

AIR  PURIFIER   FOR   ENGINE   ROOM   AND   MACHINE   SHOP 

The  contrivance  consists  of  a  tubular  casing 
adapted  for  insertion  in  a  circular  opening  in  the 
roof  of  a  building  or  the  deck  of  a  vessel.  Inside 
of  the  casing  a  sleeve  is  so  supported  as  to  leave 
an  air-passage  between  the  casing  and  the  sleeve. 
Mounted  in  the  sleeve  is  a  tube  provided  internally 
with  a  spider  or  frame,  and  at  its  upper  end  with  a 
rotatable  ingress  tube.  This  ingress  tube  likewise 
has  a  spider  or  frame  on  which  a  rod  is  centrally 
pivoted.  The  upper  end  of  the  casing  is  inclosed 


USEFUL    KNOWLEDGE  243 

by  a  hood  formed  with  a  conical  end,  through 
which  the  ingress  tube  passes.  With  the  conical 
end  of  the  hood  an  ingress  tube 
is  connected  which  communi- 
cates with  the  interior  of  the 
hood.  These  ingress  and  egress 
tubes  are  curved  in  opposite 
directions,  and  are*mounted  to 
swing  in  such  a  manner  that  the 
ingress  tube  shall  constantly 
present  its  opening  to  the  wind. 

The  ingress  tube  continually  forces  a  column  of 
air  downward  through  the  building,  and  the  egress 
tube  permits  all  warm  or  vitiated  air  to  escape. 
Any  vacuum  formed  by  ventilation,  it  is  said, 
will  be  immediately  filled  by  the  air  pressed  into 
the  cold  tube  entering  a  room  at  the  bottom.  The 
ventilator  at  the  rear  or  leeward  of  the  hood  con- 
stitutes an  air-passage,  creating  a  vacuum  below 
and  drawing  up  the  warm  air. 

HOW   TO   READ  A   GAS   METER 

The  right  hand  dial  of  the  three  used  for  actual 
measurement,  records  the  number  of  feet  by 
hundreds,  up  to  1,000,  the  center  dial  the  number 
of  thousands  up  to  10,000,  and  the  left  hand  one 
the  number  in  tens  of  thousands  up  to  100,000. 
Thus,  if  the  hands  have  passed  the  5,  6  and  7 
figures  on  these  dials  the  amount  consumed  is 
76,500,  etc. 


THERMOMETERS 


COMPARATIVE 

SCALES. 

Reau- 

Centi- 

Fahr^ 

mur, 

grade, 

enheit 

BULBS  FOR  CONVERSION. 

%  80*. 

100«. 

212«. 

76 
7* 

68 

95 
90 
85 

203 
194 
185 

Abbreviations:    F.  =  Fahrenheit,  C  = 
Centigrade,  R.  =  Reaumur 

63.1 

78.9 

174 

60 

75 

167 

56 

70 

158 

62 

65 

149 

48 

60 

140 

44 

55 

131 

42.2 

52.8 

127 

40 

50 

122 

36 

45 

113 

.33.8 

42.2 

108 

To  Convert 

32 

40 

104 

29.3 

36.7 

98 

F.  to  C.,  subtract  32   and  multiply 

88 
85.8 

35 
32.2 

95 

90 

remainder  by  f  . 

24 
21.3 

30 
26.7 

86 
80 

F.  toR.,  subtract  32  and    multiply 

20 
16 

25 
20 

77 
68 

remainder  by  f  . 

12.4 
10.2 

15.3 

12.8 

60 
55 

C.  to  F.  ,  multiply  by  f  and  add  32. 

8 

10 

50 

5.8 

7.2 

45 

R.  to  F.  ,  multiply  by  f  and  add  32. 

4 

5 

41 

1.3 
0 

1.7 
0 

35 

32 

C.  to  R.,  multiply  by  j. 

—  0.9 
—  4 

—  1.1 
—  5 

30 
23 

R.  to  C.,  multiply  by  f  • 

—  5.3 

—  6.7 

20 

-8 

-10 

14 

—  9.8 

—12.2 

10 

—12 

—15 

5 

—14.2 

—17.8 

0 

—16 

-20 

—  4 

—20 

—25 

—13 

—24 

-30 

—22 

—28 

—35 

—31 

—32 

-40 

—40 

244 


USEFUL    KNOWLEDGE  245 

STOPPING  WITH  A  HEAVY   FIRE 

When  it  becomes  necessary  to  stop  an  engine 
with  a  heavy  fire  in  the  furnace,  place  a  layer  of 
fresh  coal  on  the  fire,  shut  the  damper  and  start 
the  injector  or  pump  for  the  purpose  of  keeping  up 
the  circulation  in  the  boiler. 

TO   PREVENT   ACCIDENT   BY   THE   SHAFTING 

While  the  shafts  are  in  motion,  it  is  strictly  pro- 
hibited: a.  To  approach  them  with  waste 
or  rags,  in  order  to  clean  them.  b.  To  climb  upon 
a  ladder  or  other  convenience  in  order  to  clean  a 
shaft. 

These  parts  of  the  machinery  must  be  cleaned 
by  means  of  a  long-handled  brush  only,  and  while 
standing  upon  the  floor. 

The  workmen  charged  with  these  or  other  func- 
tions about  the  shafting  must  wear  jackets  with 
tight  sleeves,  and  closely  buttoned  up ;  they  must 
wear  neither  aprons  nor  neckties  with  loose  ends. 

Driving  pulleys,  couplings  and  bearings  are  to 
be  cleaned  only  when  at  rest.  > 

This  labor  should,  in  general,  be  performed 
only  after  the  close  of  the  day's  work.  If  per- 
formed  during  the  time  of  an  accidental  idleness 
of  the  machinery,  or  during  the  time  of  rest,  or  in 
the  morning  before  the  commencement  of  work, 
the  engineer  in  charge  is  to  be  informed. 


246  USEFUL    KNOWLEDGE 

GRAPHITE  IN   STEAM-FITTING 

The  value  of  graphite  in  making  joints  cannot 
be  overestimated.  Indestructible  under  all  changes 
of  temperature,  a  perfect  lubricant  and  an  anti- 
incrustator,  any  joint  can  be  made  up  perfectly 
tight  with  it  and  can  be  taken  apart  years  after  as 
easily  as  put  together.  Rubber  or  metal  gaskets, 
when  previously  smeared  with  it,  will  last  almost 
any  length  of  time,  and  will  leave  the  surface 
perfectly  clean  and  bright.  Few  engineers  put  to 
sea  without  a  good  supply  of  this  valuable  mineral, 
while  it  seems  to  be  almost  overlooked  on  shore. 

HOW   TO    OVERCOME  VIBRATION 

How  to  put  the  smith  shop  in  an  upper  story 
without  having  the  working  on  the  anvils  jar  the 
building,  has  been  a  problem  that  has  frequently 
given  manufacturers  trouble.  A  mechanical 
engineer '  says  it  may  be  safely  done  by  placing 
a  good  heavy  foundation  of  sheet  lead  on  the 
floor,  and  on  that  putting  a  good  thickness  of 
rubber  belting. 

Another  person  who  is  interested  in  the  problem 
has  tried  the  experiment,  with  some  success,  of 
placing  the  block,  not  on  the  floor,  but  on  the  joist 
direct,  making  a  cement  floor  up  to  the  block,  and 
over  the  wooden  floor,  reaching  back  beyond  the 
reach  of  sparks.  It  is  sometimes  said  that  black- 
smith shops  never  burn,  but  they  keep  right  on 


USEFUL    KNOWLEDGE  247 

burning  in    spite   of    theory,   and  cement   floors 
ought  to  be  helpful  in  guarding  against  fires. 

STEAM   AS   A   CLEANSING  AGENT 

For  cleaning  greasy  machinery  nothing  can  be 
found  that  is  more  useful  than  steam.  A  steam 
hose  attached  to  the  boiler  can  be  made  to  do 
better  work  in  a  few  minutes  than  any  one  is  able 
to  do  in  hours  of  close  application.  The  principal 
advantages  of  steam  are,  that  it  will  penetrate 
where  an  instrument  will  not  enter,  and  where 
anything  else  would  be  ineffectual  to  accomplish 
the  desired  result.  Journal  boxes  with  oil  cellars 
will  get  filthy  in  time,  and  are  difficult  to  clean 
in  the  ordinary  way ;  but,  if  they  can  be  removed, 
or  are  in  a  favorable  place,  so  that  steam  can  be 
used,  it  is  a  veritable  play  work  to  rid  them  of  any 
adhering  substance.  What  is  especially  satis- 
factory in  the  use  of  steam,  is  that  it  does  not  add 
to  the  filth.  Water  and  oil  spread  the  foul  matter, 
and  thus  make  an  additional  amount  of  work. 

MIXTURE  FOR   CLEANSING   RUSTY    STEEL 

Tin  putty,  10  parts;  prepared  buckshorn,  8 
parts;  spirits  of  wine,  25  parts.  Mix  to  a  paste. 
Rub  on  the  part  to  be  cleaned  and  wipe  off  with 
blotting  paper. 

HOW   TO    CUT  A   GLASS   GAUGE   TUBE 

Take  a  three-cornered  file  and  wet  it,  hold  tube 
in  left  hand  with  thumb  and  index  finger  at  the 


248  USEFUL    KNOWLEDGE 

place  where  you  wish  to  cut,  saw  it  quickly  two 
or  three  times  with  the  edge  of  the  file ;  then  take 
tube  in  both  hands,  both  thumbs  being  on  the 
opposite  side  to  the  mark  and  about  an  inch  apart, 
then  try  to  bend  the  glass,  using  the  thumbs  as 
fulcrums. 

Too  much  bearing  surface  in  a  journal  is  some- 
times worse  than  too  little. 

Steel  hardened  in  water  loses  in  strength — but 
hardening  in  oi]  increases  its  strength,  and  adds 
to  its  toughness. 

RULE  for  roughly  figuring  on  the  coal  in  a  bin 
or  box — Multiply  the  length  of  the  bin  or  box 
with  its  width  and  the  product  by  the  height  of 
the  coal  in  feet.  Multiply  the  result  by  54  for, 
fine  anthracite  coal  or  by  50  for  bituminous.  The 
answer  will  be  in  pounds.  ,  Divide  by  2,000  to  get 
tons. 

If  a  leather  belt  is  oil-soaked,  sift  Fuller's  earth 
(a  mixture  of  clay  and  silicious  matter)  or  pre- 
pared chalk  on  its  face,  and  after  a  while  remove 
it  by  scraping  with  a  sharp  edged  stick. 

A  little  damp  salt  applied  to  the  pulley  side  of  a 
leather  belt  roughens  it  and  prevents  slipping. 

Oil  is  injurious  to  rubber  belts,  but  when  a  rub- 
ber belt  slips  on  account  of  dust  and  dryness,  a 
little  boiled  linseed  oil  lightly  applied  on  the  pul- 
ley side  of  the  belt  will  remove  the  trouble. 


ELECTRICAL  MACHINERY 

ELECTRICITY 

Q.— What  is  electricity? 

A. — Electricity  is  the  name  for  the  cause  of  a 
large  and  important  class  of  phenomena  in  nature, 
such  as  attraction  and  repulsion,  heating,  luminous 
and  magnetic  effects,  chemical  decomposition,  etc. 

Q.— Is  it  a  fluid? 

,  A.— It  probably  is  not.  Nobody  knows  exactly 
what  it  is.  It  is  now  supposed  to  be  a  quality, 
possessed  to  some  degree  by  all  or  most  substances, 
consisting  in  a  peculiar  movement  or  arrangement 
of  the  molecules. 

Q.— Is  electricity  a  newly  discovered  power? 

A. — Its  most  simple  effects  were  noticed  by  a 
Greek,  Thales,  in  the  sixth  century  before  Christ. 
He  observed  that  amber,  when  rubbed  with  silk, 
attracted  light  bodies,  like  bits  of  bran,  cork  and 
the  like.  (The  Greek  for  amber  is  electron,  hence 
the  term  electricity. ) 

Q. — What  is  meant  by  positive  and  negative 
electricity? 

A.— It    is    found  that  glass  rubbed    with   silk 
attracts,   while    the    silk     repels.     Sealing     wax 
rubbed  with  silk  repels,  while  the  silk    attracts. 
249 


250  QUESTIONS    AND    ANSWERS 

The  vitreous  (glass)  electricity  is  called  positive, 
the  resinous  (wax)  electricity  is  called  negative. 

Q.— Is  electricity  always  due  to  friction? 

A.— No,  we  have  frictional  (or  statical)  and 
voltaic  (or  current)  electricity.  The  statical  is  so 
called  because  it  is  at  rest. 

Q.— Which  of  the  two  is  used  in  arts  and 
mechanics? 

A.— The  voltaic. 

Q.— How  is  it  produced? 

A. — Either  by  a  voltaic  battery,  or  by  revolving 
a  coil  of  wire  in  the  magnetic  field  between  the 
poles  of  a  steel  magnet  (electro-magnet),  or  by  in- 
ducing the  current  by  the  action  of  another  current 
or  magnet. 

Q. — What  is  induction? 

Q. — The  process  of  creating  electric  properties 
in  a  body  through  the  influence  of  a  neighbouring 
body,  having  those  properties. 

Q. — What  is  an  electro-magnetic  field? 

A. — The  space  traversed  by  the  lines  of  magnetic 
force  produced  by  an  electro-magnet. 

Q. — What  is  the  principal  difference  between 
statical  and  current  electricity? 

A. — Current  electricity  has  little  electro-motive 
force,  but  is  very  large  in  quantity.  It  has  little 
power  to  overcome  resistance  (of  a  non-conductor), 
but  it  can  do  a  great  amount  of  work.  Statical 
electricity  has  the  opposite  qualities. 


ELECTRICITY  251 

Q. — What  causes  lightning? 

A. — It  is  supposed  that  lightning  is  due  to  the 
high  potential  created  by  the  union  of  many 
minute  water-drops  into  larger  ones  and  the 
accompanying  immense  decrease  of  surface.  What 
produces  the  atmospheric  electricity,  is  unknown. 

Q. — What  is  current  electricity  mostly  used  for? 

A. — For  producing  the  electric  light,  for. elec- 
tro-plating and  for  the  transmission  of  energy. 

Q. — Is  this  manner  of  transmission  of  energy 
inexpensive? 

A. — Yes.  It  may  be  transmitted  over  miles  of 
wire,  which  could  be  done  in  no  other  way,  and 
some  dynamos  transform  as  high  as  90  per  cent  of 
the  mechanical  energy  used  in  revolving  the 
armature  into  the  energy  of  the  electric  current. 

Q. — What  is  chemical  and  thermal  electricity? 

A. — Chemical  electricity  is  produced  by  chemical 
action ;  thermal  is  produced  by  the  application  of 
heat  to  an  arrangement  of  metallic  plates. 

Q. — Does  electricity  pass  through  all  substances? 

A. — No.  Some  materials,  like  rubber,  mica  and 
fiber,  offer  such  high  resistance  that  the  current 
will  take  some  other  path.  They  are  called  non- 
conductors and  are  used  for  insulating  conductors. 

Q. — What  are  the  principal  subjects  considered 
under  the  head  of  current  electricity? 

A. — They  are  the  effects  of  the  current  in  caus- 
ing chemical  decomposition  in  electrolysis  and 


252  QUESTIONS    AND    ANSWERS 

electro-metallurgy ;  in  producing  heat  and  light  in 
a  resisting  medium ;  in  the  production  of  induced 
currents  in  a  coil  of  wire;  the  measurement  of 
electro-motive  force  (unit:  one  volt),  of  resistance 
(unit:  one  ohm),  of  the  force  of  a  current  (unit: 
one  ampere),  and  of  working  power  (unit:  one 
watt). 

Q. — How  many  kinds  of  current  are  dis- 
tinguished? 

A. — Three — continuous,  alternating  and  multi- 
phase. The  continuous  current  is  a  constant  flow 
from  the  positive  pole,  as  in  chemical  electricity. 
The  alternating  current  is  produced  by  a  rotation 
of  the  two  legs  of  a  magnet  opposite  an  armature, 
or,  in  modern  machines,  by  a  rotation  of  an 
armature  between  the  two  poles  of  a  magnet.  The 
multiphase  current  results  from  combining  3  or  more 
alternating  currents,  with  phases  displaced  with 
respect  to  each  other ;  has  definite  direction  of  flow. 

Q. — Can  you  detect  the  nature  of  a  current? 

A. — Yes.  A  magnetic  needle  introduced  into  a 
continuous  current  will  assume  a  fixed  position; 
in  an  alternating  current  it  will  swing  from  side 
to  side ;  and  with  a  multiphase  it  will  revolve. 

Q. — How  can  it  be  determined  which  is  the  north 
or  positive  pole  in  an  electro-magnet? 

A. — According  to  "Ampere's  Rule,"  the  experi- 
menter considers  himself  to  be  swimming  head 
foremost  with  the  current,  along  the  wire,  always 


ELECTRICITY  253 

facing  the  iron  core ;  then  the  north-seeking  pole 
will  always  be  at  his  left  hand. 

Q.— What  other  way  is  the  positive  or  negative 
pole  found? 

A. — First  saturate  a  piece  „<>£  white  blotting 
paper  with  a  solution  of  potassium  iodide  diluted 
in  a  glass  of  water,  parts  i  to  4.  Place  the  blot- 
ting paper  on  one  of  the  brushes,  then  hook  one 
end  of  a  piece  of  insulated  wire,  the  ends  of  which 
are  bare,  to  the  switch  and  place  the  other  end  on 
the  blotter  where  it  touches  the  brush,  and  if  it  is 
the  positive  pole  or  brush  the  blotter  on  the  under 
side  will  turn  a  brownish  color;  if  it  is  the  negative 
or  south  pole  it  will  not  affect  it. 


ELECTRICAL  TERMS 

Accumulator,  or  Secondary  Battery — An  ap- 
paratus for  storing  electrical  energy  produced  by 
another  apparatus. 

Alternate  Current  Dynamo — A  dynamo  in  which 
the  current  rapidly  alternates  or  reverses  its 
direction  from  positive  to  negative. 

Ammeter,  or  Ampere  Meter — An  instrument 
for  measuring  the  rate  at  which  a  current  passes 
through  a  conductor. 

Ampere — The  unit  by  which  the  flow  of  current 
is  measured — so  called  after  Ampere,  a  French 
scientist 


254  ELECTRICAL    TERMS 

Ampere  Hour — A  current  of  one  ampere  flowing 
for  one  hour.  When  multiplied  by  the  pressure 
in  volts  it  gives  the  consumption  of  electrical 
energy  in  Watt-hours,  1,000  of  which  form  the  B. 
T.  U.  (Kilowatt). 

Ampere's  Rule — for  rinding  the  direction  of  a 
current — A  magnetic  needle,  if  placed  near  a 
current  of  electricity  flowing  from  the  observer 
who  is  facing  the  needle,  is  deflected  to  his 
left. 

Anode — The  positive  terminal  of  an  electric 
source,  in  opposition  to  Kathode,  the  negative 
terminal. 

Arc — The  bow  of  light  produced  by  the  electric 
current  flowing  between  two  carbon  points 
(electrodes)  which  are  slightly  separated. 

Arc  Lamp — A  device  for  regulating  and  feeding 
the  carbons  of  an  electric  arc,  so  that  as  the  car- 
bons are  consumed  the  distance  between  them 
or  the  length  of  the  arc  is  continually  preserved. 

Armature — That  portion  of  a  dynamo  which 
revolves  between  the  magnets  and  in  which  the 
electric  currents  are  induced. 

Automobile — Machines  that  move  automatically 
through  electricity  or  any  other  force. 

Bare  Conductors— Electric  wires  or  conductors 
with  no  covering  or  insulation. 

Batteries,  Primary— A  set  of  cells  for  generating 
electric  currents  by  chemical  action. 


ELECTRICAL    TERMS 


255 


Bitumen  Insulation—A  prepared  bitumen  com- 
pound  used  for  covering  or  insulating  electric 
conductors. 

Board  of  Trade  Unit  (B.  T.  U.) 
— A  measurement  of  electrical 
energy  decided  upon  by  the  Board  f 
of  Trade  for  the  public  supply 
companies  to  base  their  charges 
upon.  It  is  equal  to  1,000  Watt- 
hours,  or  about  the  amount  of 
electrical  energy  consumed  by 
seventeen  i6-candle-power  lamps 
burning  for  one  hour. 

Brush  of  Dynamo — An  arrange- 
ment of  copper  wires,  gauze  or 
strips  soldered  together  at  one 
end,  for  collecting  the  current  from 
the  commutator  of  a  dynamo. 

Buckling — A  bending  and  dis- 
placement of  the  plates  of  an 
accumulator,  caused  usually  by  dis- 
charging the  current  too  rapidly. 

Cables,  Electric— Usually 
applied  to  electric  conductors, 
consisting  of  stranded  wires,  to  dis- 
tinguish them  from  single  wires. 

Calibration — Standardizing  or  correcting  of  any 
instrument  to  the  standard  value,  such  as  volt- 
meter, ammeter,  etc. 


256  ELECTRICAL    TERMS 

Candle,  The  Standard — A  spermaceti  wax 
candle,  burning  120  grains  per  hour,  taken  as  the 
standard  of  reference  for  measuring  the  lumi- 
nosity, or  candle  power  of  any  light. 

Carbons — For  arc  lamps,  rods,  or  pencils,  gen- 
erally made  from  powdered  gas-coke,  hardened 
into  shape  by  baking,  and  used  for  the  electric 
arc. 

Casing,  Wood — A  covering  or  sheath  of  wood, 
generally  containing  two  grooves,  used  for  the 
protection  of  insulated  wires. 

Cathode— The  negative  terminal  of  an  electric 
source.  See  Anode. 

Cell — A  box  or  other  receptacle  containing  the 
elements  and  solutions  necessary  for  the  produc- 
tion of  storage  of  electrical  energy.  A  number  of 
such  cells  are  termed  a  battery. 

Change  Over  Switch — A  switch  for  changing 
electrical  connections  from  one  source  of  supply 
to  another. 

Charging— Filling  or  storing  an  accumulator 
with  electrical  energy. 

Circuit — A  system  of  metallic  or  other  conduct- 
ing bodies  placed  in  continuous  contact  and 
capable  of  conveying  an  electric  current. 

Commutator — Bars  of  copper  and  sheets  of 
isinglass  to  separate  them,  which  form  the  ends 
of  the  armature  coils,  and  from  which  the  current 
is  collected. 


ELECTRICAL    TERMS  257 

Conductivity— The  facility  offered  to  the  pass- 
age of  electric  currents  through  a  substance. 

Conductor — A  substance  through  which  elec- 
tricity will  pass,  but  applied  principally  to  those 
in  which  v.ery  little  resistance  is  offered  to  the 
passage  of  a  current,  such  as  copper  wire. 

Continuous  Current — A  current  from  a  dynamo 
or  battery  which  does  not  vary  in  direction  and 
flows  continuously. 

Controller — An  automatic  magnetic  regulator 
for  a  dynamo-electric  machine. 

Converter  —  The  inverted  transformer  or 
induction  coil,  used  on  alternating  current 
systems. 

Coulomb — The  unit  of  electrical  quantity. 
That  quantity  of  electricity  which  would  pass 
in  one  second  through  a  resistance  of  one  ohm 
with  a  pressure  of  one  volt. 

Current,  Electric  —  The  flow  of  electricity 
through  any  conductor. 

Creeping — A  leakage  of  electricity  over  the 
surface  of  an  insulating  body,  caused  by  a  film  of 
moisture  and  dirt,  or  deposit  from  evaporation, 
forming  a  conductor. 

Dielectric — Another  term  for  insulator. 

Diaphragm — A  plate  or  sheet  securely  fixed  at 
its  edges,  as  a  drum  head,  and  capable  of  being 
set  in  vibration,  like  a  telephone  diaphragm. 

Dimmer — A  choking  coil  employed    on    trans- 


x$8  ELECTRICAL    TERMS 

former  circuits  to  regulate  the  potential.  Used  ir 
theaters  to  turn  the  lights  up  or  down. 

Distributing  Board  —  A  board  from  which 
branch  wires  or  cables  are  led  to  various  positions 
from  main  conductor. 

Dynamo — A  machine  for  producing  electricity 
by  transforming  mechanical  work  into  electrical 
energy. 

Earth  or  Ground — Term  used  to  denote  the 
leakage  of  electricity  (short  circuit). 

Earth  Return — A  circuit  in  which  the  earth 
forms  part  of  the  conducting  path.  It  is  usually 
formed  by  connecting  the  ends  of  an  insulated 
line,  either  to  gas  or  water  pipes,  or  to  metal 
plates  buried  in  the  earth. 

Electric  Motor — A  machine  similar  to  a  dynamo, 
but  used  for  conveying  electrical  energy  into 
mechanical  power. 

Electrical  Energy — The  capacity  of  electricity 
for  doing  work,  whether  for  electric  lighting  or 
for  power  or  traction  purposes.  It  is  directly  pro- 
portionate to  the  amount  of  current  and  its  pres- 
sure. Thus  by  multiplying  the  flow  of  current  in 
amperes  by  the  pressure  in  volts  the  amount  of 
electrical  energy  is  obtained  in  watts. 

Electricity,  Thermal — Produced  by  the  applica- 
tion of  heat  to  an  arrangement  of  metal  bodies. 

Electrodes — The  two  terminals  forming  thr 
positive  and  negative  poles  in  a  battery. 


ELECTRICAL    TERMS  259 

Electrolier — A  device  for  suspending  a  group  of 
incandescent  lamps ;  the  equivalent  of  chandelier, 
gasalier,  etc. 

Electrolysis — The  process  of  chemically  separat- 
ing the  component  parts  of  any  substance  by 
means  of  electricity. 

Electrolyte — Any  substance  capable  of  under- 
going a  chemical  dissolution  by  an  electric  current. 

Electro-Magnet — A  bar  of  soft  iron  temporarily 
magnetized  by  the  influence  of  an  electric  current 
passing  through  a  wire  encircling  it. 

Electro-Metallurgy — The  science  or  process  of 
electrically  decomposing  solutions  or  salts  of 
metals. 

Electro-Motive  Force  (usually  written  E.  M.  F. ) 
— The  cause  of  the  transfer  of  electricity,  and 
therefore  the  force  which  supplies  the  pressure  to 
an  electric  current. 

Electro-Plating — The  depositing  of  metals  by 
means  of  electricity  upon  the  surface  of  another 
metal  or  other  substance. 

Field,  Electro-Magnetic — The  space  trayersed 
by  the  lines  of  magnetic  force  produced  by  an 
electro-magnet. 

Filament  of  an  Incandescent  Lamp — The  thread- 
like substance  composed  usually  of  vegetable 
matter  (such  as  bamboo,  cotton,  paper,  etc.), 
which  by  the  application  of  intense  heat  has  been 
carbonized 


260  ELECTRICAL    TERMS 

Forming  Plates— The  operation  of  bringing  the 
plates  of  accumulators  into  proper  chemical  con- 
dition. 

Galvanic  Electricity — Produced  by  chemical 
action ;  so  termed  after  Galvani. 

Galvanometer — An  instrument  used  in  testing, 
for  showing  the  flow  of  an  electric  current. 

Glow — A  white,  bright  heat. 

Henry — The  practical  unit  of  self-induction.  A 
secohm  or  quadrant. 

Horse-Power — To  find  the  power  of  engine 
required  to  run  a  dynamo,  multiply  voltage  by 
amperes,  then  multiply  the  answer  by  number 
of  lights  lit  and  divide  by  746.  Answer  in 
Watts. 

Hour  Lamp — A  service  of  electric  current  which 
will  maintain  one  electric  lamp  one  hour. 

Incandescent  Lamp — A  glass  bulb  or  globe 
from  which  the  air  has  been  exhausted,  contain- 
ing a  carbonized  filament  which  comes  to  a  white 
glow  on  the  passage  of  an  electric  current. 

Induced  Current — Electricity  produced  by  the 
influence  that  one  magnetic  or  electrified  body  has 
on  another  not  in  contact  with  it. 

Induction — The  influence  that  one  magnetic  or 
electrified  body  has  over  another  produced  by  a 
dynamo. 

Installation — Plant. 

Insulation  —  The  non-conducting  substance  ap- 


ELECTRICAL    TERMS  261 

plied  to  the  surface  of  an  electrical  conductor  to 
prevent  leakage. 

Insulator — Any   non-conducting  material,  such 
as    gutta-percha,     india- 
rubber,  china,  glass,  oko- 
nite,  etc. 

Jablochkoff  —  The    in-, 
ventor  of  the  Jablochkoff  ] 
candle,   an   arrangement  * 
of   carbons    placed    side 
by  side,    and    separated 
by  a  suitable    non-con- 
ducting  substance,   such 
as    kaolin,   and  used   to 
form  an  electric  arc. 

Kaolin — The  finest  of 
china  clay. 

Kathode— See  Cathode. 

Kilowatt — 1,000  Watts. 

Mains  —  Copper  cables 
or  other  means  used  for 
the  purpose  of  conveying 
electricity,  chiefly  applied 
to  the  larger  conductors  INCANDESCENT  LAMP  AND 

SWITCH  SOCKET. 

or  cables. 

Megohm — A  unit  of  resistance;  equal  to  one 
million  ohms. 

Meter,  Electric — An  instrument  for  measuring 
the  amount  of  electrical  energy  used. 


L#2  ELECTRICAL    TERMb 

Milliampere — The  one- thousandth  part  of  aa 
ampere. 

Motor— Any  machine  which  may  be  used  for 
imparting  mechanical  power.  A  dynamo  running 
the  reverse  way. 

Negative — See  Positive. 

Non-Conductor — Any  substance  which  resists 
the  passage  of  electricity,  chiefly  applied  to  those 
in  which  this  quality  is  strongly  marked. 

Ohm — The  unit  by  which  the  resistance  offered 
to  the  passage  of  an  electric  current  is  measured ; 
the  legal  ohm  is  the  resistance  offered  by  a  column 
of  pure  mercury,  106  centimeters  in  length  and  i 
millimeter  square  in  cross-section ;  or  the  resist- 
ance offered  by  a  copper  wire  32  gauge,  10  ft. 
long  (from  Dr.  G.  S.  Ohm). 

Okonite — Composition  of  tape  and  rubber 
mixed,  to  wrap  joints,  to  insulate,  etc. 

Parallel  Wiring — Term  used  to  express  the  sys- 
tem of  electrical  distribution,  in  which  each  lamp 
has  its  individual  flow  and  return  wires,  no  current 
passing  through  two  lamps  in  series. 

Permanent  Magnet  —  A  piece  of  steel  or 
loadstone  containing  enduring  magnetic  force, 
and  requiring  no  electric  current  to  mag- 
netize it. 

Photometer — An  instrument  for  measuring  th^ 
Intensity  of  light. 

Pilot  Lamp — A  test  lamp  frequently  used  in  th 


ELECTRICAL    TERMS  263 

engine-room,  serving  to  denote  the  E.  M.  F.  of 
the  current  from  the  dynamo. 

Plugs,  Safety-Fuse — The  movable  portion  of  the 
safety-fuse,  containing  the  fusible  wire. 

Plugs,  Shoe — The  movable  ^portion  of  a  shoe  or 
small  attachment,  to  which  are  attached  the 
flexible  wires  in  connection  with  the  portable  lamp. 

Poles — General  term  to  express  the  positive 
and  negative  conductors  in  electricity,  or  the  north 
and  south  extremities  of  a  magnet. 

Positive  and  Negative — Terms  used  to  dis- 
tinguish the  polarity  of  wires  in  an  electric 
circuit;  the  flow  is  termed  the  positive  pole,  and 
the  return  the  negative. 

Potential — As  heat  tends  to  equalize  between 
two  bodies  of  different  temperature,  so  electricity 
tends  to  equalize  between  two  points  of  different 
potential.  As  the  difference  in  level  between  two 
water  reservoirs  connected  by  a  pipe  determines 
the  velocity  of  the  equalizing  process,  so  the 
difference  of  potential  determines  the  electro- 
motive force  of  the  equalizing'  electric  current. 
Another  determining  part  is  the  resistance  of  the 
connecting  conductor;  as  the  diameter  of  the 
connecting  pipe  and  friction  are  for  the  two  water 
reservoirs. 

Primary  Cables  and  Wires — In  an  electrical 
system  of  distribution  where  high  pressure  cur- 
rent is  transformed  to  low  pressure,  all  cables  and 


264  ELECTRICAL    TERMS 

devices  conveying  the  high -pressure  current  are 
termed  primary. 

Resistance — The  opposition  afforded  by  any 
substance  to  the  passage  of  electricity. 

Resistance  Coil — A  coil  of  wire  used  for  creating 
a  certain  desired  resistance  to  the  passage  of  a 
current. 

Rheostat — An  instrument  consisting  of  one  or 
more  resistance  coils  for  varying  the  resistance  in 
an  electrical  circuit. 

Rocker — An  attachment  on  the  bearing  of  a 
dynamo  to  permit  of  the  adjusting  of  the  brushes. 

Safety  Fuse,  or  Cut-Out — A  device  for  auto- 
matically stopping  the  flow  of  electricity  in  case 
of  accidents  or  defects  in  the  conductors ;  a  single- 
pole  safety  fuse  controls  only  one  wire,  a  double- 
pole  controls  both  the  positive  and  negative. 

Scaling  in  Accumulators — The  formation  of  a 
deposit  upon  the  plates  which  prevents  the  acid 
from  acting  upon  them. 

Secondary  Wires — The  low-pressure  coils  in  a 
transformer,  which  are  acted  upon  by  the  primary 
or  high-pressure  wires. 

Series,  Electro-motive — An  arrangement  of  the 
metals,  so  that  each  is  positive  with  reference  to 
those  which  follow  in  the  list,  and  negative  to 
those  which  precede.  In  dilute  sulphuric  acid  the 
order  is  zinc,  lead,  iron,  copper,  silver,  platinum, 
carbon. 


ELECTRICAL    TERMS  265 

Series  Wiring— Where  the  positive  pole  of  each 
cell  is  connected  to  the  negative  pole  of  the  next 
cell.  In  the  multiple  arc,  all  the  positive  poles  are 
wired  to  one  post  and  all  the  negative  ones  to 
another. 

Short  Circuit— A  term  used  to  express  any 
metallic  or  other  connection  formed  accidentally 
between  a  positive  and  negative  wire,  by  which 
the  current  may  take  a  short  cut,  instead  of  com- 
pleting its  journey  through  the  lamp,  motor,  etc. 

Sunbeam-Lamps—Incandescent  lamps  of  high 
candle  power. 

Switch— An  arrangement  for  breaking  or  com- 
pleting an  electric  circuit. 

Telpherage — A  system  of  overhead  transporta- 
tion of  goods  by  means  of  cars  running  between 
two  steel  rails  top  and  bottom  of  car  from  which 
an  electric  current  is  obtained  to  work  motors 
fixed  on  one  or  more  of  the  cars. 

Tension — The  same  for  electricity,  as  pressure 
for  steam. 

Terminal — Attachment  screw,  by  which  a  cur-, 
rent  enters  or  leaves  any  electrical  apparatus  or 
conductor. 

Thermo-Pile — A  combination  of  certain  metals 
coupled  together  so  as  to  produce  electricity  by 
the  application  of  heat. 

Three-Wire  System — A  system  of  distribution 
in  which  two  dynamos  and  three  wires  are  so 


266  ELECTRICAL    TERMS 

connected  that  the  third  wire  serves  as  flow  and 
return  to  the  other  two  wires.  Besides  a  consider- 
able saving  in  the  cost  of  the  cables,  a  constant 
potential  service  results. 

Transformer  —  An  instrument  for  reducing 
or  transforming  a  high  pressure  current  to  a  low 
one,  or  the  reverse. 

Transmission  of  Power  —  The  operation  of 
conveying  or  transmitting  power  from  one  point 
to  another. 

Turbine — A  machine  for  utilizing  the  force  or 
fall  of  running  water. 

Two  or  Three-Way  Switch — A  switch  having 
two  or  three  contact  pieces  attached  to  con- 
ductors, which  by  means  of  a  movable  handle 
permits  the  current  to  be  sent  into  either  con- 
ductor. 

Unit,  Board  of  Trade.     See  B.  T.  U. 

Unit,  of  Current.     One  Ampere. 

Unit,  of  Electrical  Energy.     One  Watt. 

Unit,  of  Pressure.     One  Volt. 

Unit,  of  Resistance.     One  Ohm. 

Volt — The  unit  by  which  the  electro-motive  force 
or  pressure  of  current  is  measured.  It  is  the  E.  M. 
F.  that  will  cause  a  current  of  one  ampere  to  flow 
against  a  resistance  of  one  Ohm.  The  volt  is 
based  on  the  product  of  one  Daniell  cell.  Named 
after  Volta,  an  Italian  scientist  and  inventor  of  the 
Voltaic  column. . ' ' 


THE    DYNAMO    AND    ITS    PARTS  267 

Volt-Meter  —  The  instrument  for  measuring 
the  pressure  or  E.  M.  F.  of  a  current. 

Vulcanized  India  Rubber  —  India  rubber, 
treated  with  suphur,  etc.,  to  preserve  and  make 

it  hard.      To  combine  india  rubber  with  sulphur 

% 
by  heat. 

Watt,  The — The  unit  by  which  electrical  work 
is  measured.  It  is  equal  to  the  current  of  one 
ampere  flowing  at  a  pressure  of  one  volt. 

The  amount  of  energy  is  found  by  multiplying 
the  amount  of  current  by  its  voltage  pressure.  For 
instance,  a  current  of  10  amperes  with  a  pressure 
of  100  volts,  represents  1,000  Watts.  See  B.  T.  U. 

Wire,  Flexible — A  conductor  composed  of  a 
large  number  of  fine  wires  stranded  together,  so 
making  it  flexible. 

Wires,  Electric — Small  conductors,  other  than 
the  mains. 


THE  DYNAMO    AND   ITS    PARTS   AND 
ATTACHMENTS 

Q. — What  is  a  dynamo? 

A. — The  dynamo,  or  better,  the  dynamo-electric 
machine,  converts  energy  (motion  of  piston  and 
disc)  into  electricity  by  the  aid  of  the  permanent 
magnetism  present  in  certain  iron  portions.  The 
electricity  generated  then  reacts  on  the  iron, 
heightening  its  magnetism;  the  increased  mag- 
netism again  p'roduces  more  powerful  electrical 


268 


QUESTIONS    AND    ANSWERS 


effects,  and  so  on,  until  a  limit  is  reached.     The 
limit  depends  partly  on  the  velocity  of  motion 
partly  on  the  quality  and  proportions  of  the  iron 
and    wire    in  the   dynamo,   and    partly    on    the 
resistance  throughout  the  circuit. 


Q.  — What  are  the  parts  of  a  dynamo? 

A. — An  electro-magnet  M,  M,  M,  which  is 
made  of  two  columns  of  soft  iron,  encircled  by 
coils  of  insulated  copper  wire,  and  which  are 
united  together  by  cross  pieces  top  and  bottom. 


THE    DYNAMO    AND    ITS    PARTS  269 

Between  the  poles  or  magnet  revolves  the 
armature  A,  which  consists  of  a  number  of  coils 
of  insulated  wire  wound  around  an  iron  core. 

The  ends  of  each  coil  are  connected  to  copper 
strips  (segments,  or  bars)  plaped  side  by  side, 
forming  a  cylinder  known  as  the  commutator  C, 
from  which  the  current  is  collected.  Generally 
two  sets  of  so-called  brushes  or  collectors  B  are 
fixed  upon  the  rocker  (yoke)  D,  which  remains 
stationary,  unless  it  is  necessary  to  adjust  the 
position  of  the  brushes  around  on  the  commutator. 
(See  pages  273,  285.)  Attached  to  these  brushes, 
one  set  being  positive  and  the  other  negative,  are 
cables  E,  E,  conveying  the  two  main  currents 
(positive  and  negative)  generated  to  the  switch  at 
the  top  (side)  of  dynamo,  by  means  of  which  con- 
nection can  be  made  with  the  main  supply  cables. 
An  attachment  F,  F  to  convey  the  current  to  the 
electro-magnet  is  at  the  top  of  the  two  magnet 
coils.  G  is  the  driving  pulley. 

The  armature  should  be  kept  up  to  the  proper 
speed  found  stamped  on  field  plate.  The  speed  is 
known  by  a  speed  indicator  and  timepiece.  >  Com- 
mutator should  be  kept  quite  clean  and  bright  by 
wiping  it  occasionally  with  a  rag  when  running. 
If  necessary  it  may  be  cleaned  with  sandpaper 
before  starting  for  regular  run,  the  brushes  being 
raised  off  the  commutator. 

The  brushes  for  service  must  be  set  firmly  in 


270  QUESTIONS    AND    ANSWERS 

their  holders  and  rest  well  on  the  commutator  so 
as  to  make  good  contact.  They  must  be  set 
exactly  opposite  each  other  and  no  brush  wires  (if 
made  so)  left  straggling. 

The  rocker  yoke  holding  the  brushes  should  be 
moved  up  or  down,  so  as  to  adjust  them  to  the 
neutral  point,  according  to  the  amount  of  current 
the  dynamo  is  supplying.  When  properly  adjusted 
there  should  be  no  sparking. 

Q.  — What  is  a  commutator? 

A. — It  consists  of  a  number  of  metal  cylinder 
segments  insulated  from  each  other  by  mica. 

Q.— What  is  the  exact  function  of  the  com- 
mutator? 

A.  — It  serves  to  rectify,  or  send  in  one  direction, 
the  vibrations  or  opposing  currents  created  by 
the  alternate  passing  of  each  pole  of  the  armature 
before  the  north  and  south  pole  of  the  magnets. 

Q. — How  is  it  done? 

A. — It  is  done  in  different  ways.  In  some  sys- 
tems, springs,  sliding  over  the  half  cylinders,  are 
so  arranged  that  they  always  are  one  in  positive,  • 
and  the  other  in  negative  condition.  In  other 
systems  the  armature  is  rotated  so  rapidly  (1,600 
revolutions  per  minute,  and  more)  that  the  waves 
of  current  succeed  each  other  at  such  short  inter- 
vals, that  they  appear  like  a  steady  current,  no 
break  in  continuity  being  perceptible  to  ordinary 
tests. 


THE    DYNAMO    AND    ITS    PARTS  271 

Q. — Does  this  rapid  magnetization  and  demag- 
netization produce  heat? 

A.  — Yes,  overheating  of  the  dynamo  is  a  draw- 
back of  this  system  of  commutation. 


h  2LECTIUCAL  POWER  6T08AOB 
ACCUluULATOa  CELLS. 


Q.  — What  is  the  accumulator? 

A.  — It  is  a  battery  of  cells  in  which  the  electrical 
power  is  stored.  It  is  also  called  a  secondary 
battery.  * 

Q. — What  is  such  a  battery  used  for? 

A. — The  wet  battery  (large  cut)  is  used  for 
storing  electricity  to  maintain  a  limited  number  of 
lights  after  the  dynamo  has  been  shut  down.  The 
dry  accumulator  (small  cut)  is  used  for  automobile 
vehicles,  small  lamps,  etc.  • 


272 


QUESTIONS    AND    ANSWERS 


ELECTRIC  CYCLE  LAMP  AND 
ACCUMULATOR. 


fOCKET  ELECTK1C  ACCUMU-    ELECTRIC  HAND  L6.US 
tATOR.  ACCUMULATOR. 


Q. — What  is  a  rheostat? 

A.  — It  is  an  instrument  for  regulating  or  adjust- 
ing a  circuit,  so  that  any  required  degree  of  resist- 
ance may  be  maintained;  a  resistance  coil. 

Q. — Give  an  ex- 
ample of  the  way  in 
which  the  rheostat  is 
used?  See  cut  l^T 

A. — When  the  dy- 
namo is  first  speeded 
to  proper  speed  it 
shows  a  dull  light 


and    through    the 

rheostat  or  controller  the  voltage  is  raised  up  to 

no,  the  proper  voltage  for  incandescent  lamps. 

Q. — What  is  a  transformer? 

A. — It  is  used  for  tapping  a  low  voltage  circuit 
into  a  high  voltage  circuit,  as  in  connecting  an 
incandescent- lamp  to  an  arc  light  circuit. 

Q.— What  is  a  "step  up"  transformer? 


THE    DYNAMO    AND    ITS    PARTS 


273 


A. — It  is  used  for    the    reverse,   getting  high 
voltage  from  a  low  voltage  circuit. 

Q. — On  what  principle  are  transformers  based? 

A. — On  greater  or  lesser 
resistance. 

Q. — What  is  a  converter? 

A.  —  The  inverted  trans- 
former, or  induction  coil,  used 
on  alternating  current  sys- 
tems. 

Q. — Are  the  same  brushes 
used  for  dynamos  and  motors?  c 

A.— No.    The  motor  brushes 
are  almost  exclusively  compressed  carbon ;  on  the 
dynamo  copper  plates  or  wires  are  used. 


Q. — How  are  the  pointer  and  scale  used? 

A. — They  are  attached  to  the  rocker  stud,  and 
serve  to  secure  a  sparkless  position  of  *  the 
brushes  by  adjusting  the  arrow  to  the  scale  every 


274  QUESTIONS    AND    ANSWERS 

time  the  load  (number  of  lamps  in  circuit)  is 
changed. 

Q.— What  is  a  Daniell  cell? 

A. — A  zinc  plate  immersed  in  dilute  sulphuric 
acid  contained  in  a  porous  vessel,  outside  of  which 
is  a  perforated  copper  plate  surrounded  by  a 
solution  of  copper  sulphate.  The  action  is  as 
follows:  The  reaction  between  the  zinc  and  sul- 
phuric acid  produces  zinc  sulphate  and  hydrogen. 
The  latter,  however,  instead  of  collecting  on  the 
copper  plate,  unites  with  the  copper  sulphate, 
forming  sulphuric  acid  and  metallic  copper.  The 
former  goes  to  keep  up  the  supply  of  acid  in  the 
inner  vessel  and  the  latter  is  deposited  on  the 
copper  plate.  The  consumption  of  copper  sul- 
phate is  made  good  by  a  supply  of  crystals  in  a 
receptacle  at  the  top. 

Q. — What  is  a  gravity  cell? 

A. — It  is  a  modification  of  the  Daniell  cell,  in 
which  the  porous  vessel  is  done  away  with.  The 
two  liquids  are  separated  by  their  specific  gravities ; 
the  copper  sulphate  surrounds  the  copper  plate  at 
the  bottom,  and  the  zinc  sulphate  surrounds  the 
zinc  plate  at  the  top. 


HOW  TO  MAKE  TRACING-PAPER 

Place  your  sheets  of  double-crown  tissue  paper 
in  one  smooth  pile,  and  apply  to  the  top  sheet  a 
mixture  of  mastic  varnish  and  oil  of  turpentine, 
equal  parts  in  bulk,  using  a  flat  brush,  2  inches 
broad.  Hang  each  sheet,  when  coated,  over  a 
line  to  dry.  You  may  trace  on  this  paper  with  ink. 


VARIETIES   OF   THE   DYNAMO 

Q.—  How  would  you  classify  dynamo-electric 
machines  in  general? 

A.— In  generators  and  motors.  A  generator  is 
a  machine  for  the  conversion  of  mechanical  energy 
into  electrical  energy,  by  means  of  magneto- 
electric  induction.  A  motor  is  a  machine  for  the 
conversion  of  electrical  energy  into  mechanical 
energy  by  means  of  magneto-electric  induction. 

Q. — Why  are  there  so  many  different  generators? 

A. — Some  are  more  economical  for  certain  pur- 
poses ;  some  give  a  constant  potential,  others  give 
a  constant  current,  etc. 

Q. — What  is  a  magneto-electric  machine? 

A. — It  is  similar  to  a  dynamo,  except  that  the 
fields  are  permanent  magnets  instead  of  electro- 
magnets. 

Q.— What  is  a  compound  dynamo  machine? 

A. — One  whose  fields  are  wound  with  two  coils, 
one  of  large  wire,  being  in  series  with  the  arma- 
ture, the  other  of  smaller  wire  in  parallel  with  the 
armature.  This  arrangement  makes  the-dynamo 
self-regulating. 

Q. — What  is  a  multipolar  dynamo? 

A. — A  bi-polar  dynamo  has  only  one  pair  of 
field  magnets,  a  multipolar  one  has  more  than 
one  pair. 

275 


276  QUESTIONS    AND    ANSWERS 

Q. — What  is  an  alternating  current  dynamo? 

A. — A  dynamo  without  a  commutator.  The 
fields  are  usually  separately  excited,  as  a  direct 
current  is  required  for  their  excitation. 


ELWELL-PARKER  ALTERNATE  CURRENT  DYNAMO,' 


Q. — What  is  meant  by  "separately  excited"? 

A. — The  field  coils  receive  the  current  for  their 
excitation  from  some  source  other  than  their  own 
armature. 

Q. — What  is  meant  by  closed-coil? 

A. — The  coils  are  connected  continuously  to- 
gether in  a  closed  circuit,  being  attached  to 


VARIETIES  ,OF    THE    DYNAMO  277 

successive  bars  of  the  commutator,  as  in  the 
Gramme  and  most  direct-current  dynamos. 
When  not  connected  continuously,  although  at- 
tached to  successive  bars  of  the  commutator,  as 
in  the  Brush  or  T.  H.  arc  dynamo,  they  are  termed 
open-coil. 

Q.— What  is  shunt? 

A.— A  dynamo  so  constructed  that  the  entire 
current  must  pass  through  the  field  coils,  is  called 
a  series  dynamo;  where  an  additional  path 
(external  circuit)  is  provided,  so  that  only  a  por- 
tion of  the  current  passes  through  the  field  coils, 
this  parallel  connection  is  called  shunt.  The 
fields  are  "wound  in  shunt  with  the  outside 
circuit." 

Q. — What  is  meant  by  short-shunt? 

A. — When  the  shunt  coils  of  the  fields  of  a  com- 
pound dynamo  are  connected  to  the  brushes  of  the 
machine,  not  to  the  binding  posts  or  external 
circuit  as  in  the  long-shunt. 

Q. — What  is  a  "shunt  and  separately-excited" 
dynamo? 

A. — It  is  compound- wound,  one  field  coil,  receiv- 
ing current  from  the  armature,  the  other  from  a 
separate  source. 

Q. — How  many  kinds  of  series  dynamos  are 
there? 

A. — Three,  all  compound,  as  follows: 

i.     Series  and  magneto,  in  which  the  circuit  of 


278  QUESTIONS    AND    ANSWERS 

a  magneto  machine  is  connected  in  series  with  its 
armature  and  fields. 

2.  Series  and  separately-excited,  in  which  the 
fields  have  two  circuits,  one   in   series  with  the 
fields  and  external  circuit,  the  other  being  sepa- 
rately excited,  used  to  maintain  constant  potential 
at  the  terminals. 

3.  Series  and  shunt,  one  of  the  field  coils  of 
which  is  in  series  with  the  armature  and  outside 
circuit,  the  other  in  shunt  with  the  armature. 

Q. — What  is  meant  by  synchronizing? 

A. — Modifying  the  phase  of  two  alternating  cur- 
rent dynamos  so  that  they  may  be  connected  in 
parallel. 

Q. — What  is  the  three-wire  system? 

A. — A  combination  of  Edison's  for  the  distribu- 
tion of  electric  current  for  constant  potential 
service,  in  which  three  wires  are  used  instead  of 
two,  one  being  a  neutral  wire.  Two  dynamos  are 
employed. 

Q. — What  is  constant  potential  service? 

A.  — An  even  flow  of  current.  In  a  water  pump 
the  air  chamber  similarly  renders  the  pressure  and 
flow  even  or  constant.  See  Potential,  p.  263. 

Q. — What  is  the  difference  between  a  dynamo 
and  a  motor? 

A. — The  dynamo  converts  mechanical  work  into 
an  electric  current,  which  the  motor  then  converts 
back  into,  or  uses  in,  mechanical  work. 


MANAGEMENT  AND  CARE  OF  A  DYNAMO 

THE    PLANT 

Q.— -What  rules  should  be  observed  in  placing 
a  dynamo? 

A— It  should  be  placed  in  a  Veil-lighted,  clean, 
cool  and  dry  place,  and  so  that  it  is  easily  access- 
ible from  all  sides. 

Q.— What  should  not  lie  near  a  dynamo? 


Generator  Panel:  Front,  Side  and  Back  Views. 


A. — Iron,  steel,  bolts,  nails,  tools  of  any  descrip- 
tion, or  waste,  filings   or  dust,  as  they  may  be 
attracted  by  the  powerful  magnetism  or  the  cur- 
rent of  air  created  by  the  revolving  armature. 
279 


280 


QUESTIONS    AND    ANSWERS 


Q.— Where  should  the  switch-board  and  fuse 
blocks  be? 

A.— Like  the  engine,  they  should  be  so  near 
the  dynamo  that  the  whole  plant  can  be  taken 


t 


Feeder  Panel :  Front,  Side  and  Back  Views. 

in  at  one  glance,  but  so  far  apart  that  there  is  no 
danger  of  a  short  circuit. 

Q. — Of  what  should  the  bases  of  all  cut-outs, 
switches,  lightning  arrestors,  etc.,  be  made? 

A. — Marble,  slate,  or  porcelain. 

Q.— How  should  connections  be  made? 

A. — Soldered  and  thoroughly  insulated. 

Q. — What  kind  of  wire  should  be  used  in  damp 
places? 

^  —Rubber-covered  wirea- 


THE    CARE    OF    A    DYNAMO 

Q. — Would  you  use  metal  staples  in  electric 
light  or  power  work? 

A. — No.     Use  porcelain  insulators. 

Q. — What  is  an  insulator? 

A. — It  is  a  non-conductor,  preventing  the  cur- 
rent from  leaving  the  wire.  (See  page  312.) 

Q.— In  cleat  work,  what  kind  would  be  best  to 
use? 

A. — Those  with  V-shaped  grooves;  they  clamp 
firmly. 

Q. — How  many  cleats  should  be  used  to  turn  a 
corner  or  angle,  and  why? 

A. — Two,  to  make  it  neat  and  workman-like. 

Q. — Would  it  be  safe  and  proper  to  use  a  bare 
wire  in  any  part  of  the  wiring  throughout  a  build- 
ing? 

A  — No.     All  wires  should  be  properly  insulated. 

Q. — How  do  you  test  the  insulation  of  a  wire. 
to  see  whether  it  affords  the  required  resistance? 

A.— It  should  be  tested  to  not  less  than  250 
Megohms  per  mile  in  dry  places  and  600  Meg- 
ohms per  mile  in  damp  places.  The  test  must  be 
taken  with  an  electro-motive  force  of  not  letfs  than 
loo  volts  after  the  insulated  cables  have  been  in 
water  at  60  degrees  Fahrenheit  for  24  hours,  and 
with  one  minute's  electrification. 

Q. — What  should  be  put  in  a  line,  between  the 
cut-out  switch  and  the  street  where  the  wire 
entered  the  building? 


282  QUESTIONS    AND    ANSWERS 

A. — Loops  of  wire  known  as  drip  loops. 

Q. — What  style  of  belting  should  be  used  for  a 
dynamo  or  motor? 

A. — It  should  be  a  light  double,  endless  and 
rivetless  one. 

Q. — Why  should  the  belt  be  endless  and  not 
laced? 

.  A. — Because  every  time  the  laced  joint  passed 
over  the  dynamo  pulley  the  lights  would  fluctuate 
(flicker). 

Q.— If  the  belt  is  endless,  how  is  the  slack  taken 
up? 

A. — Nearly  all  dynamos  and  motors  are  provided 
with  a  frame  and  belt-tightening  apparatus  com- 
prised of  one  center  or  two  side  screws  and 
foundation  slides  on  which  the  dynamo  rests; 
with  these  the  dynamo  or  motor  can  be  forced 
back  and  the  belt  tightened. 

Q. — How  much  should  a  belt  be  tightened? 

A. — Enough  to  prevent  extreme  slipping. 

STARTING  THE   DYNAMO 

Q. — What  should  be  done  every  day  before 
starting  a  dynamo? 

A. — The  dynamo  tender  should  examine  the 
binding  posts,  the  commutator  and  brushes,  also 
see  that  the  contacts  are  clean  and  firmly  tight- 
ened by  the  set  screws.  Any  dust  and  dirt  should 
be  most  carefully  removed  with  soft  rags  and  a 


THE    CARE    OF    A    DYNAMO  283 

bellows,  as  they  cause  the  majority  of  all  the 
troubles  and  annoyances. 

Q. — What  rules  should  be  observed  in  starting 
the  dynamo? 

A.  — Always  start  the  machine  to  running  with 
the  main  switch  open  and  the  brushes  raised  from 
the  commutator,  so  all  the  working  parts  can  be 
seen ;  be  sure  that  the  rheostat  is  at  zero.  Then 
drop  the  brushes  on  the  commutator,  then  see  that 
the  voltage  is  correct  on  volt-meter.  If  the 
brushes  spark,  rock  the  brush  holder  quadrant 
forward  or  backward  around  the  commutator  until 
a  sparkless  place  is  found,  then  close  the  main 
switch.  When  running  drop  a  little  oil  on  tjie  end 
of  finger  and  rub  in  the  palm  of  hand,  then  pass 
the  finger  gently  over  the  commutator  lengthwise. 

Q. — How  high  would  you  cause  the  volt-meter 
needle  to  rise? 

A. — The  proper  voltage  for  incandescent  lights 
is  no  volts.  If  run  up  to  115,  there  is  danger  of 
burning  out  the  filaments. 

Q. — What  rules  must  be  observed  in  disconnect- 
ing the  dynamo? 

A. — In  disconnecting  the  dynamo  after  it  has 
been  used  for  charging  the  accumulators  or  supply- 
ing lights,  etc.,  the  engine  should  be  eased  down, 
dynamo  switch  opened,  and  the  brushes  raised 
from  the  commutator  to  cool,  also  to  be  free  in 
case  the  armature  was  turned  the  reverse  way. 


284  QUESTIONS    AND    ANSWERS 

The  copper  brushes  should  be  fil^d  to  one  bevel, 
also  kept  clean  and  free  from  oil,  copper  dust,  etc. 


RUNNING   THE    PLANT 

Q. — How  and  when  would  you  test  the  circuit? 

A. — It  should  be  tested  every  day  for  grounds, 
by  means  of  the  detector,  galvanometer  or  a  mag- 
neto bell. 

Q. — If  there  was  a  ground,  how  would  you 
locate  it? 

A. — By  disconnecting  the  circuit  in  different 
places,  and  testing  each  section  separately  until 
located. 

Q. — Give  various  reasons  for  excessive  sparking 
of  commutator  and  brushes  of  a  dynamo  or  motor? 

A. — Poor  condition  of  the  brushes  and  holders ; 
faulty  adjustment  of  brushes ;  surface  of  the  com- 
mutator rough  or  covered  with  dirt  and  grease; 
the  insulation  of  one  field  magnet  coil  injured  and 
the  coil  short-circuited  in  itself. 

If  one  magnet  is  excited  more  than  the  other, 
one  brush  will  spark  more  than  the  opposite  one, 
in  the  same  way  as  if  improperly  adjusted. 

Two  or  more  segments  of  commutator  short- 
circuited. 

Dynamo  or  motor  overloaded.  Overloading  will 
also  cause  considerable  heating  of  the  armature 
and  fields.  Overloading  of  the  dynamo,  or  motor, 


THE    CARE    OF    A    DYNAMO  285 

may  be  caused  by  poor  insulation  of  the  external 
circuit,  thus  causing  a  considerable  amount  of 
current  to  escape  froirf  one  pole  to  the  other. 

Grounding  of  the  external  wires,  which  fre- 
quently happens  in  rainy  weather. 

In  arc  lighting,  lamps  may  be  fed  by  too  strong 
a  current ;  in  incandescent  lighting,  too  many  lamps 
may  be  put  on  the  leads. 

Q. — Name  the  different  causes  of  the  eating 
away  of  the" segments  of  a  commutator? 

A. — Too  much  tension,  too  much  contact  sur- 
face, brushes  not  set  properly,  or  not  far  enough 
around  on  the  commutator. 

Q. — What  will  cause  flat  spots  on  the  face  of 
commutator? 

A. — Badly  soldered  armature  wire  connections, 
also  soft  spots  in  the  copper  segments. 

Q. — How  would  you  know  when  brushes  have 
not  enough  contact  or  pressure  on  commutator? 

A. — By  a  peculiar  snapping  noise. 

Q. — What  is  the  effect  of  a  brush  being  too  long, 
or  pressing  too  hard? 

A. — It  will  cut  the  commutator,  emitting  strong 
spattering  sparks. 

Q. — How  can  the  brushes  be  made  to  press 
harder  or  lighter  on  the  commutator? 

A. — By  adjusting  the  brush  holders. 

Q. — How  are  brushes  moved  on  commutator? 

A. — By  the  yoke  (quadrant).      (See  page   273.) 


286  QUESTIONS    AND    ANSWERS 

Q. — Why  are  they  moved  around  on  the  com- 
mutator, and  when? 

A. — When  more  or  fewer  amperes  of  electricity 
are  necessary  for  lights,  power,  etc. 

Q.— How  are  the  different  kinds  of  brushes 
adjusted? 

A. — Practically  all  alike.  They  should  be  set 
at  a  bevel  of  45°  to  the  commutator.  Each  brush 
should  cover  at  least  one  segment  and  two  insula- 
tions to  make  the  current  as  nearly  continuous  as 
possible. 

Copper  wire  or  copper  leaf  brushes  are  filed  to 
a  45°  bevel  and  the  commutator  wears  them 
to  a  concave.  Carbon  brushes  are  concaved  by 
putting  coarse  sandpaper  on  the  commutator, 
rough  side  up,  and  by  drawing  it  to  and  fro. 

Q. — Where  should  the  brushes  be  set? 

A.— At  neutral  (opposite)  points. 

Q. — How  would  you  make  a  copper  brush? 

A.  — Cut  the  strips  the  width  of  the  opening  in 
the  -brush  holder,  and  take  so  many  of  them  that 
the  brush  will  pass  through  the  holder  easily, 
and  solder  them  together  at  one  end.  The  same 
for  wire,  gauze  and  other  copper  brushes. 

Q.— How  thick  should  a  carbon  brush  be? 

A. — One-half  thicker  than  the  commutator  bar 
to  make  it  strong  enough. 

Q. — Is  it  safe  to  touch  the  two  opposite  brushes 
(positive  and  negative)  at  any  time  while  running? 


THE    CARE    OF    A    DYNAMO  287 

A. — No,  for  if  the  motor  or  dynamo  be 
grounded  (short-circuited)  the  full  voltage  would 
be  received  and  cause  either  paralysis  or  death. 

Q. — When  a  motor  or  dynamo  becomes  very 
hot,  to  what  would  you  lay  the  trouble? 

A. — It  being  overloaded,  or  poor  connections. 

Q. — How  can  stationary  motors  be  reversed? 

A. — By  changing  (crossing)  the  wires  on  the 
yoke  or  fields,  also  reversing  the  brushes. 

Q. — Suppose  the  twine  covering  the  armature 
wires  near  the  commutator  segments  happened  to 
unravel  while  running,  what  would  you  do? 

A. — Open  switch  and  after  motor  or  dynamo 
has  stopped  remove  the  remaining  twine. 

Q. — Would  it  not  interfere  with  the  machine? 

A. — No.  It  is  there  to  keep  out  as  much  dust  as 
possible  from  in  between  the  armature  wires. 

REPAIRS 

Q. — What  causes  the  insulation  of  one  or  more 
coils  around  the  armature  to  char  and  crumble  off? 

A. — Excessive  heat  caused  by  short  circuit,  poor 
connections,  overloading,  and  cotton  waste,  etc., 
being  attracted  at  the  end  of  the  dynamo  and 
pressed  between  the  armature  and  pole  pieces. 

Q. — In  what  way  will  the  waste  injure  the 
armature? 

A. — By  scaling  off  the  insulation  from  the  wire 
in  some  places  or  bursting  the  metal  bands  encir- 
cling the  armature. 


288  QUESTIONS    AND    ANSWERS 

Q. — Do  these  injuries  extend  below  the  outside  / 
layer  of  wire? 

A. — Sometimes,  but  not  very  often. 

Q. — Can  the  wires  be  insulated  without  being 
taken  to  a  repair  shop? 

A. — Yes,  by  carefully  lifting  one  wire  at  a  time 
just  high  enough  to  wrap  it  with  silk  tape,  and 
thus  insulate  it. 

Q.— What  causes  the  field  magnet  to  short- 
circuit  and  burn  the  insulation? 

A. — By  getting  parts  of  the  field  wire  in  contact 
with  the  iron  core. 

Q. — What  should  be  done  in  such  trouble? 

A. — Unwind  the  wire  until  the  damaged  part  is 
reached,  and  after  insulating  it  properly,  it  should 
be  wound  back  on  the  cores. 

Q. — How  are  field  magnets  wound  and  un- 
wound? 

A. — By  placing  the  field  horizontally  between 
the  two  centers  of  a  turning  lathe. 

Q. — What  would  you  do  after  having  wrapped 
and  insulated  all  the  injured  parts  of  an  armature? 

A. — Drive  the  wires  back  into  their  positions  by 
means  of  a  hard  wood  block  and  hammer,  after 
which  give  them  two  or  three  good  coatings  of 
shellac  varnish. 

Q. — If  the  injury  was  below  the  outside  layer, 
what  should  be  done? 

A. — Take  the  armature  to  a  regular  shop  and  let 


THE    CARE    OF    A    DYNAMO  289 

them  do  the  repairing,  as  they  have  the  proper 
tools  to  do  the  work. 

Q. — Suppose  you  had  to  replace  an  old  com- 
mutator with  a  new  one,  how  would  you  proceed 
to  do  it? 

A.— Take  the  armature  out  from  between  the 
poles,  and  place  the  two  ends  of  the  shaft  on 
wooden  horses.  Mark  the  wires  leading  from  the 
armature  to  the  commutator  by  attaching  little 
tags  with  numbers,  to  make  sure  of  the  proper 
place  of  each  wire  after  taking  off  the  commutator. 
Then  disconnect  these  wires  from  the  correspond- 
ing copper  bar  of  the  commutator,  either  by 
unscrewing  the  set  screw,  or  unsoldering  the  con- 
nections by  means  of  a  hot  soldering  iron.  After 
this  is  done  remove  the  commutator,  clean  the 
shaft  and  connections  and  put  the  new  com- 
mutator carefully  in  its  proper  position,  and 
connect  the  armature  wires  in  proper  turn  to  the 
corresponding  copper  bars  of  the  commutator  by 
means  of  set  screws,  or  hard  soldering.  Great 
care  must  be  taken  not  to  short-circuit  any  part  of 
the  commutator  with  drops  of  solder. 

Q. — Why  do  electrical  engineers  and  linemen 
wear  rubber  gloves  and  rubber  soles? 

A. — Because  rubber,  like  glass,  is  a  non-con- 
ductor of  electricity.  Live  wires  should  never  be 
touched  without  one  or  the  other,  as  instant  death 
may  occur. 


MEASUREMENTS   OF  ELECTRICITY 

Q.— What  is  a  dyne? 

A. — The  unit  of  force.  The  force  which,  in  one 
second,  can  impart  a  velocity  of  one  centimeter 
per  second  to  a  mass  of  one  gramme. 

•Q. — Why  are  these  terms  not  given  in  U.  S. 
measurements,  such  as  ounces  and  inches? 

A. — Because  scientists  all  over  the  world  use 
the  decimal  system,  and  electricity  has  been 
developed  by  scientists  exclusively. 

Q.— What  is  an  erg? 

A.  — The  work  done  in  moving  a  body  through 
a  distance  of  one  centimeter  with  the  force  of  one 
dyne.  A  dyne  centimeter.  Ten  million  ergs  = 
one  joule.  The  joule  is  the  practical  C.  G.  S.  unit 
of  electrical  energy  or  work.  (C.  G.  S.  =  cen- 
timeter— gramme — second. ) 

Q.— What  is  a  watt? 

A. — The  unit  of -electric  work  or  power,  equal 
to  one  joule  per  second. 

One  H.  P.  =  746  watts. 

The  number  of  watts  is  numerically  equal  to 
the  product  of  the  current  passing,  times  the 
voltage  which  produces  that  current.  i  volt 
times  i  ampere  =  i  watt ;  3  volts  times  3  amperes 

9  watts,  etc. 

A  kilowatt  is  1,000  watts. 
290 


MEASUREMENTS    OF    ELECTRICITY        291 

Q. — What  is  a  coulomb? 

A. — The  unit  of  electrical  quantity.  That 
quantity  of  electricity  which  would  pass  in  one 
second  through  a  resistance  of  one  ohm  with  a 
pressure  (force)  of  one  volt.  *  ^ 

Q. — What  is  an  ampere? 

A. — The  unit  of  electric  current.  That  rate  of 
flow  which  would  transmit  one  coulomb  per 
second. 

Q. — What  is  an  ampere-hour? 

A. — The  equal  of  one  ampere  flowing  for  one 
hour,  or  3,600  coulombs. 

Q. — What  is  an  ohm? 

A. — The  practical  unit  of  electrical  resistance. 
A  resistance  through  which  an  electric  current  of 
one  ampere  will  flow  under  a  pressure  of  one 
volt. 

The  legal  ohm,  now  internationally  adopted, 
equals  the  resistance  of  a  column  of  mercury  106 
centimeters  in  length,  having  an  area  of  cross- 
section  of  one  square  millimeter,  at  o°  C.,  or  32°  F. 

A  section  of  wire  having  a  resistance  equal  to 
the  legal  ohm  is  used  as  a  "standard  oh*m." 
1000  feet  of  T\j-inch  copper  wire  has  a  resistance 
of  very  nearly  one  ohm ;  a  mile  of  common  iron 
telegraph  wire  has  a  resistance  of  about  13  ohms. 

A  megohm  =  one  million  ohms. 

Q.— What  is  the  Law  of  Ohm? 

A. — The  strength  of  a  continuous  current  (C) 


292  QUESTIONS    AND    ANSWERS 

is  directly  proportional  to  the  electro-motive  force 
(E)  in  the  circuit,  and  inversely  proportional  to 
the  resistance  (R)  in  it.  It  is,  therefore,  the  e. 
m.  f.  divided  by  the  resistance.  C  =~  ;  E  =  C  X 

ff  R. 

R;  R  =  -. 

C 

Q.— What  is  a  volt? 

A.— The  practical  unit  of  electric  pressure,  or 
electro-motive  force.  The  pressure  required  to 
move  one  ampere  against  one  ohm.  The  volt  is 
based  on  the  product  of  one  Daniell  cell. 

Q.  — What  similarity  is  there  between  electrical 
terms  and  steam  terms? 

A. — The  volts  may  be  compared  to  pounds  of 
steam  pressure;  the  resistance  to  friction;  the 
wire  to  the  pipe ;  the  coulomb  to  the  quantity  of 
steam  passing  through  the  pipes;  the  ampere  to 
the  rate  at  which  the  steam  passes;  the  watt  to 
the  amount  of  work  performed  (H.  P. ). 

Q. — What  difference  do  you  make  between 
"force"  and  "power"? 

A. — In  common  language,  they  are  used  as 
equivalents,  but  in  science  the  following  distinc- 
tion is  made : 

Force  is  the  cause  of  a  change,  such  as  from 
rest  to  motion,  or  in  condition,  etc. ;  power  is  the 
rate  of  the  expenditure  of  energy.  Electricity, 
steam,  gravity,  expansion,  etc.,  are  forces;  we 
speak  of  horse-power,  candle-power,  gross  and  net 
power,  etc. 


MEASUREMENTS    OF    ELECTRICITY       293 

Q.— How  much  of  a  H.  P.  is  required  to  main- 
tain a  steady  light  for  a  i6-candle-power  incandes- 
cent lamp? 

A. — About  one-tenth,  or  10  lamps  to  a  H.  P. 

Q. — How  many  volts  for  an  arc  light? 

A. — 220. 

Q. — Can  arc  lights  and  incandescent  be  run  on 
the  same  circuit? 

A.  — Yes,  by  the  use  of  the  transformer. 

Q.— How  is  the  efficiency  of  a  dynamo  deter- 
mined? 

A. — By  dividing  the  electrical  energy  produced 
by  the  mechanical  energy  expended  in  driving 
the  dynamo. 

Q. — How  do  you  arrive  at  the  amount  of  elec- 
trical power  spent? 

A. — By  multiplying  the  amount  of  current  by 
its  pressure.  For  example,  a  current  of  10 
amperes  with  a  pressure  of  100  volts  represents 
1,000  watts  (i  kilowatt).  A  current  of  20  amperes 
with  a  pressure  of  50  volts  represents  the  same 
power  (1,000  watts). 

Q.— What  is  meant  by  the  B.  T.  U.? 

A. — It  means  the  consumption  of  electrical 
energy  of  one  thousand  watts  in  one  hour. 

Q. — How  are  the   electric   currents  measured? 

A. — Either  chemically  or  mechanically. 

Q. — Explain  the  chemical  system? 

A. — It  is  based  on  the  simple  fact  that  one 


294  QUESTIONS   AND   ANSWERS 

ampere  of  electricity  will  deposit  from  sulphate  of 
zinc,  under  standard  conditions,  a  definite  weight 
of  metal.  This  type  of  meter  is  a  small  electro- 
plating battery  through  which  a  certain  proportion 
of  the  current  is  carried— the  proportion  being 
accurately  determined  by  the  relative  sizes  of  the 
meter  wires  and  the  shunts — with  the  result  that 
one  of  the  two  plates  is  decreased  and  the  other 
increased  in  weight,  according  to  the  amount  of 
current  consumed. 

Q. — Where  and  how  is  the  meter  placed? 

A.— It  should  be  placed  in  a  clean,  dry  place 
and  connected  to  the  inside  service  with  moisture- 
proof  wire.  It  must  always  be  protected  by  a 
service  cut-out ;  never  placed  between  the  cut-out 
and  the  street  service.  It  should  be  in  a  place 
not  likely  to  freeze,  also  where  the  inspector  can 
have  easy  access  to  it.  The  meter  should  be 
screwed  fast  to  a  well-seasoned  board,  not  less 
than  i  inch  thick  and  well-covered  with  asphal- 
tum  against  the  wall.  Never  place  more  lights 
on  a  meter  than  it  is  intended  to  carry. 

Q. — What  test  is  made,  and  how  is  it  made? 

A. — It  is  necessary  to  find  the  positive  clips  and 
mark  them.  For  this  two  things  must  be  known : 

Which  side  of  meter  is  connected  to  street,  and 
which  of  the  two  outside  wires  is  positive. 

The  first  is  found  by  tracing  the  conductors  or 
opening  the  circuit. 


MEASUREMENTS    OF    ELECTRICITY        295 

The  second,  by  testing  with  a  blotting  paper 
saturated  with  a  solution  of  potassium  iodide. 
With  the  moistened  paper  in  hand  press  it 
against  the  upper  and  middle  binding  posts. 

A  brown   mark  will  appear  where  the    paper 


.Meter  Fed  on  Right  Side. 

(See  cuts  A  and  B.) 

*A" — When  top  post  gives 
brown  mark,  right  hand 
clips  are  positive. 

"B" — When  middle  post 
gives  brown  mark,  left  hand 
clips  are  positive. 

Meter   Fed   on   Left   Side. 
(See  cuts  C  and  D.) 

"C" — When  top  post  gives 
brown  mark,  left  hand  clips 
-are  positive. 

"D" — When  middle  post 
gives  brown  mark,  right 
hand  clips  are  positive. 


127 

+  CIJPS 
A. 


+  CUPS 

B. 


+  CLIPS 

C. 


+  CLIPS 

D. 


*LAMP  > 


touched  the  positive  post.     By  following  rule  the 
positive  clips  can  be  determined.     The  clips  are 


296        MEASUREMENTS    OF    ELECTRICITY 

« 

at  the  top  of  meter  and  the  chemical  bottles  set 
under  them. 

If  the  center  wire  is  not  brought  into  the  meter, 
the  lowest  post  must  be  used  for  the  middle  in 
using  foregoing  rules. 

All  positive  clips  should  be  carefully  marked. 
The  positive  plate  can  be  known  by  it  being  next 
to  the  head  of  the  bolts  which  bolt  the  two  plates 
together. 

Sometimes  the  positive  plate  has  a  tag  attached, 
which  prevents  mistakes. 

Q. — Explain  the  mechanical  meter? 

A. — Of  these  there  are  many  varieties,  those 
most  in  use  being  the  Thompson- Houston  watt 
meter  and  the  Westinghouse  or  Schallenberg 
ampere  meter,  both  of  which  are  small  motors 
driven  faster  or  slower  as  the  demand  for  current 
is  greater  or  less,  and  communicating  their  action 
to  a  train  of  wheels  with  dials  like  those  of  a  gas 
meter,  so  that  they  may  be  verified  by  burning  a 
given  number  of  lamps  for  an  hour  and  compar- 
ing the  dials  at  the  beginning  and  end  of  the 
time.  The  meter  record  is  taken  usually  once  a 
month,  and  the  bills  are  based  upon  these  records 
with  as  much  certainty  as  though  electricity 
were  visible. 


THE  MOTOR  AND  CONTROLLER 

Q. — -What  is  an  electric  motor? 

A.— The  reverse  of  the  dynamo,  used  for  con- 
verting electricity  into  mechanical  work. 

Q.^-When  is  the  work  of  an  electric  motor  at 
its  maximum? 


[•ELECTRIC-  MOTOR. 

A. — According  to  the  "law  of  Jacobi,"  when  the 
counter  E.  M.  F.  is  equal  to  half  the  E.  M.  F. 
expended  on  the  motor,  or  the  impressed  E.  M.  F. 

Q. — What  are  stationary  motors  used  for? 

A. — For  running  elevators,  machinery,  dyna- 
mos, etc. 

Q.— Where    does   a    stationary    motor   get   its 

power  from? 

297 


298 


THE    MOTOR    AND    CONTROLLER 


A. — From  a  dynamo,  or  generally  from  a  three- 
wire  system  set  of  dynamos. 

Q. — What  voltage,  amperes  and  speed  has  a  15 
H.  P.  motor? 

A. — Generally  220  voltage,  and  any  amount  of 
amperes  it  may  need  and  1,600  speed  per  minute. 

Q. — What  different  systems  of  using  electricity 
for  traction  are  in  use? 

A. — The  overhead  trolley,,  the  underground 
trolley,  the  storage  battery  and  third-rail  systems. 


Q. — How  are  the  brushes  set  on  the  commutator 
of  a  car  or  engine  motor? 

A. — Directly  against  the  commutator  and  op- 
posite, instead  of  aslant  as  on  stationary  motors. 

Q.—What  voltage  and  H.  P.  are  the  motors  of 
elevated  roads? 


Railway  Motor. 

THIRD  RAIL  SYSTEM  WITH  SLIDING 
FEEDER  SHOE 


IZ3      Eli]      EBl     DEJ 

SIDE  VIEW 

OF 
MOTOR  TRUCKS 


300 


QUESTIONS    AND    ANSWERS 


A. — Generally  2,000  volt  type  and  100  H.  P. 

Q. — How  many  are  usually  placed  under  a  car? 

A.  — Two — one  at  each  end  of  car,  so  as  to  avoid 
the  need  of  a  turn  table. 

Q. — What  system  is  generally  used? 

A. — The  third-rail  system.     (See  page  299.) 

Q.  — Can  the  car  be  run  in  both  directions  from 
either  end? 

A. — Yes,  by  reversing  the  motor  through  the 
controller  box. 

Q. — How  is  the  electric  current  transmitted  from 
the  third  rail  to  the  controller  and  motor? 

A. — By  a  shoe  sliding  on  the  third  rail.  The 
shoe  may  be  raised  from  the  rail  by  a  short  ful- 
crum lever  in  the  controller  room,  thus  breaking 
the  circuit. 


Diagram  of  Method 
of  Suspension. 


Q. — How  is  the  motor  of  a  surface  trolley  car 
suspended  and  geared  to  the  wheels? 


THE  MOTOR  AND  CONTROLLER 


301 


A.— It  is  suspended  with  springs  and  a  frame 
between  the  wheels  and  truck. 


Railway  Motor. 

The  armature  axle  is  geared  to  the  wheel  so 
that  the  armature  pinion  turns  about  four  times  to 
a  single  turn  of  the  wheels. 

THE  CONTROLLER 

Q. — What  is  a  controller  and  its  duty? 

A. — It  consists  of  two  switches  (see  cut,  page 
302),  each  having  its  own  separate  operation  to 
perform.  The  controlling  cylinder  (switch)  No. 
2  proper  is  used  simply  to  make  the  different  com- 
binations required  to  obtain  the  proper  regulation 
of  the  speed  of  the  car.  The  second  switch,  or 
small  handle,  is  also  of  a  cylindrical  form,  but  is 
used  for  either  breaking  the  circuit  or  reversing 
the  motor,  either  forward  or  back. 

Q. — Can  a  controller  be  compared  to  a  rh'eostat? 

A. — Yes,  its  function  of  controlling  the  speed  of 
the  car  can  be  compared  to  the  working  of  the 
rheostat  in  increasing  or  decreasing  the  resistance. 

Q. — Will  switch  No.  i  of  the  controller  cut  off 
the  current  if  moved? 


302 


QUESTIONS    AND    ANSWERS 


A. — Yes,  the  slightest  movement  cuts  the  cur- 
rent entirely  off. 

Q. — How  many  notches  has  the  current  switch? 
Name  them? 

A. — Three — go  ahead,  back  up,  center  cut-out. 


Q. — How  is  the  resistance  provided  on  an  elec- 
tric controller? 

A. — A  considerable  amount  of  resistance  is  pro- 
vided in  the  shape  of  bands,  ringers  or  strips  of 
iron  or  nickel  steel. 

Q. — How  is  this  resistance  subdivided? 


THE  MOTOR  AND  CONTROLLER    303 

•A. — Into  a  considerable  number  of  parts  so  that 
it  can  be  cut  down  gradually. 

Q. — How  many  notches  has  a  controller  dial 
plate,  and  what  is  their  purpose? 

A. — Generally  7,  and  they  are  there  to  indicate 
the  increase  of  speed  gradually  -and  uniformly  by 
•  continually  lowering  the  resistance  of  circuit. 

Q. — When  the  motorman  moves  the  large  handle 
No.  2  around  on  the  dial  (notch  plate),  what  does 
it  do? 

A.  — It  connects  a  coil  of  wire  on  the  motor  with 
trolley  (feeder)  wire  each  notch  it  is  moved. 

Q. — Suppose  the  controller  handle  No.  2  stood 
in  the  seventh  notch  and  the  current  switch  No.  i 
was  suddenly  turned  on,  what  would  be  the  result? 

A.  — The  fuse  strips  would  blow,  or  melt. 

Q. — What  are  cut-out  plugs  or  strips? 

A.  — They  are  fusible  wire  and  are  used  to  save 
overcharged  or  heated  wires  from  melting. 

Q. — To  what  could  the  above  be  compared  so  as 
to  be  easily  understood? 

A. — To  an  attempt  at  starting  a  steam  engine 
suddenly  at  full  speed  instead  of  gradually  turn- 
ing on  the  steam  with  throttle. 

Q. — Compare  the  principle  of  controller  box 
and  coils  of  motor  with  the  steam  engine? 

A. — It  is  the  same  as  placing  the  reverse  lever 
in  center  notch  so  valve  equally  covers  both  steam 
ports,  then  opening  the  steam  valve  full,  this 


304  BALDWIN    AND    WESTINGHOUSE 

acting  as  the  current  switch,  and  the  reverse  lever 
as  the  controller  switch.  When  ready  to  start 
drop  the  reverse  lever  or  controller  down  one 
notch ;  if  more  steam  or  current  is  required  drop 
it  another  notch,  and  so  on  until  the  full  power 
or  current  is  passing  into  cylinder  or  motor  coils 
(fields). 


THE  BALDWIN  AND  WESTIXGHOUSE  ELECTRIC 
ENGINE  has  solved  the  problem  of  a  locomotive 
running  120  miles  an  hour. 

In  appearance  this  new  wonder  does  not  betray 
its  qualities.  The  motors  are  incased,  so  that 
hardly  any  mechanism  is  in  sight.  The  electric 
headlight  and  the  pilot  alone  disclose  its  character 
as  a  motor  car  or  locomotive. 

The  locomotive  weighs  150,000  Ibs.  and  is  37 
feet  long  over  the  pilot 

The  frame  is  made  of  lo-inch  rolled  steel  chan- 
nels, covered  by  a  one-half  inch  rolled  steel  plate 
over  the  entire  floor,  giving  enormous  strength  to 
resist  blows  in  collisions,  etc. 

This  frame  is  carried  on  two  trucks,  with  all  the 
modern  devices  of  springs,  for  swinging  motion 


ELECTRIC    ENGINE  305 

and  free  movement.  The  trucks  are  built  very 
strong  and  they  are  of  the  swiveling  type,  so  they 
may  go  around  any  curve  passable  for  an  ordinary 
freight  car. 

The  geared  connection  between  the  axles  and 
the  electric  motors  permits'*  of  any  gear  ratio 
desired. 

The  driving  wheels  may  be  connected  by  par- 
allel rods  for  pulling  heavy  trains,  as  such  rods 
would  not  permit  one  pair  of  wheels  to  slip  with- 
out the  other. 

The  motors  are  directly  beneath  the  car  floor, 
between  the  two  trucks,  and  are  "iron-clad"  con- 
sequent pole  motors. 

They  are  entirely  encased  in  thin  steel  shells, 
so  as  to  be  protected  from  all  injury  under 
normal  conditions  of  service. 

The  armatures  are  laminated,  being  made  up 
of  thin  slotted  discs  of  steel.  'In  the  slots  the 
armature  wires  are  placed.  The  commutators  are 
of  the  best  forged  copper  with  mica  insulation. 
The  motors  have  the  highest  grade  of  insulation. 
Power  is  furnished  by  the  third-rail  system. 

At  both  ends  is  a  controller.  The  path '  of  the 
current  may  be  divided  so  as  to  pass  to  both 
motors  independently,  or  it  may  be  sent  through 
one  motor  to  the  other. 

The  braking  system  has  some  unique  features. 
The  compressed  air-brake  is  used.  The  engineer's 


306  HEATING    AND    COOKING 

valve  is  of  the  standard  Westinghouse  type. 
When  the  handle  of  the  brake  valve  is  put  at 
"emergency"  for  a  sudden  stop,  pneumatic  action 
breaks  the  circuit  at  the  same  time  as  it  applies 
the  brakes. — A  special  reversing  switch  acts  on 
the  motors. — The  automatic  air-pump  is  driven  by 
electricity,  its  special  motor  being  directly  con- 
nected and  without  gear. 

The  interior  of  this  locomotive  is  that  of  an 
observation  car,  and  very  handsome. 

Our  120  miles  an  hour  locomotive  is  ready  for 
us,  but  we  are  not  quite  ready  for  it.  Before  we 
can  risk  flying  across  the  country  at  such  speed, 
all  grade  crossings  must  be  abolished  and  the 
whole  present  R.  R.  signal  system  must  be 
changed.  Signals  are  now  about  a  mile  apart, 
while  the  new  locomotive  cannot  stop  within  less 
than  one  and  a  half  miles  of  clear  way. 

ELECTRICITY  FOR  HEATING. — To  fit  heating  and 
cooking  utensils  for  the  use  of  electricity,  a  thin 
film  of  enamel  or  cement  is  spread  over  the  outer 
saucepan,  griddle,  kettle  or  heater.  Then  iron, 
platinum  or  other  high  resistance  wire  is  laid 
zigzag  over  it,  with  copper  wire  connections  made 
to  the  two  ends;  and  more  of  the  cement  or 
enamel  is  spread  over  the  wires  so  as  to  com- 
pletely embed  them.  When  enamel  is  used  the 
apparatus  is  put  in  a  kiln  and  burnt  on  similar  to 
the  ordinary  iron  cooking  utensils.  In  both 


BY    ELECTRICITY 


307 


methods  the  film  of  enamel  or  cement  insulating 
the  heating  wires  is  put  on  so  thin  and  is  so  good 
a  conductor  of  heat  that  the  heat  generated  by 
the  electricity  is  rapidly  conveyed  to  the  utensil 


ClflDDLE» 

to  be  heated.  Electricity  can  thus  be  sent  through 
the  wires  without  fear  of  overheating  them.  This 
would  not  be  possible  if  they  were  exposed  to  the 
air,  which  does  not  conduct  heat,  but  radiates  it. 


308       STATIONARY  MOTOR  AND   CONNECTIONS 

To  start  motor,  quickly  throw  in  switch  4.  Then 
move  rheostat-handle  3,  slowly  over  the  arc,  until 
stopped  by  magnet  to,  which  holds  it  while  motor 
runs.  The  nearer  the  handle  approaches  the  mag- 
net, the  larger  a  number  of  high-resistance  wire  coils 
in  the  rheostat  box  transmit  the  current,  which  has 
full  flow  when  handle  reaches  magnet.  To  stop 
motor,  throw  switch  4  out,  and  move  handle  3  off 
the  arc. 


The  motor,  i,  in  the  cut  is  series  wound,  one 
pole  connected  with  two  .binding  posts  of  revers- 
ing switch,  2 ;  the  other  pole  connects  with  handle, 
3.  5,  51  are  safety-fuses,  6  is  the  volt-meter,  7  the 
ampere-meter,  which  at  8  connects  with  rheostat 
graduation  arc.  Fuse  51  connects  with  third 
binding  post  on  switch,  2.  By  throwing  lever,  9, 
to  the  left,  the  direction  of  the  current,  and  with 
it  the  motion  of  the  motor,  is  reversed. 


ELECTRIC    WIRING 

CONDUCTIVITY 

No  part  or  particle  of  any  substance  on  earth 
can  ever  get  lost.  It  may  change  its  form,  but  it 
cannot  get  away  from  the  earth.  There  is  now 
exactly  as  much  water  on  earth  as  there  was  one 
thousand  years  ago,  not  even  one  drop  more  or 
less,  while  there  is,  of  course,  a  constant  change 
in  its  distribution  over  the  globe,  in  the  proportions 
of  its  three  forms  (gas,  liquid,  ice),  and  in  its 
combinations  with  other  substances.  Heat  con- 
sumed in  expansion,  etc.,  is  called  "latent  heat." 

So,  also,  electricity,  like  any  other  force,  cannot 
get  lost,  but  it  may  change  its  form.  When  an 
electric  current  meets  resistance  its  quantity  is 
decreased,  and  the  difference  can  be  indirectly  but 
accurately  measured  by  the  increased  temperature 
of  the  resisting  substance.  Current  electricity 
not  transmitted  is  converted  into  heat. 

The  several  metals  vary  as  much  in  their  power 
of  transmitting  electric  currents  (conductivity)  as 
they  do  in  other  respects.  Silver  and  'copper 
possess  the  greatest  conductivity,  tin  and  lead  the 
smallest.  The  same  fact  may  be  stated  thus :  Tin 
and  lead  offer  the  greatest  resistance  to  an  electric 
current,  silver  and  copper  the  least.  Any  sub- 
stance that  offers  great  resistance  is  called  a  bad 
309 


310  ELECTRIC    WIRING 

conductor ;  the  less  the  resistance  (or,  the  greater 
the  conductivity),  the  better  a  conductor  is  the 
substance. 

Conductivity  is  nearly  zero  for  glass,  sulphur, 
resin ;  it  is  very  low  for  most  liquids  and  for  gases. 
It  varies  not  only  with  varying  temperature,  but 
also  with  varying  tension,  torsion,  or  pressure.  It 
stands  in  proportion  to  the  cross-section  area  of  the 
conductor  (wire). 

The  following  table  shows  at  a  glance  that  in 
the  list  of  the  metals  named  the  heat  evolved  by 
an  electric  current  increases  in  the  inverse  ratio 
as  the  conductivity  decreases.  The  conductivity 
of  gold  is  z/z  of  that  of  copper,  the  heat  evolved  is 
I  or  i^  times  that  of  copper.  The  conductivity 
of  tin  is  *4  of  that  of  copper,  the  heat  evolved  is  6 
times  as  large: 


Conver-  Conduct- 
sion  ing 

to  heat.  power. 

Silver 6  to  120 

Copper 6  to  120 

Gold 9  to  80 

Zinc 18  to  40 


Conver-  Conduct- 

sion  ing 

to  heat.  power. 

Platinum...  30  to      24 

Iron 30  to      24 

Tin 36  to      20 

Lead  72  to      10 


Silver  wire  conducts  120  units  out  of  126,  losing 
6;  iron  wire  conducts  24  out  of  54,  losing  30;  lead 
conducts  10  out  of  82,  losing  72. 

Silver,  copper  and  gold  are  excellent  for  con- 
ducting strong  currents;  platinum  and  iron  are 
used  where  very  light  currents  are-  required,  as 
in  telegraphing;  lead  is  used  where  great  resist- 


ELECTRIC    WIRING  311 

ance  is  desirable  to  check  too  strong  a  current,  as 
in  safety-fuses ;  platinum  is  used  in  incandescent 
lamps  because  its  expansion  in  heat  is  equal  to 
that  of  glass ;  zinc  and  tin  find  minor  employment, 
as  stated  further  on. 

For  traction  and  electric  lighting  very  strong 
currents  are  needed,  and  the  conductors  are,  there- 
fore, made  of  copper  wire  of  a  size  proportionate 
to  the  rate  of  flow  desired,  gold  and  silver  being 
excluded  by  their  costliness. 

Copper  can  be  procured  in  sufficient  quantity,  is 
therefore  cheap  enough,  and  is  very  durable  and 
flexible.  The  purer  copper  is  the  better.  The 
law  does  not  allow  an  alloy  containing  less  that  96 
per  cent  of  pure  copper  for  electrical  purposes. 

Copper  that  has  become  brittle  from  some  cause 
can  be  made  soft  again  (annealed)  by  heating  it 
dark  cherry  and  plunging  into  cold  water. 
INSULATION 

As  dry  air  is  a  non-conductor,  bare  copper 
wires  will  conduct  a  strong  electric  current  without 
losing  any  of  it  (without  leakage).  This  is  why 
telegraph,  arc  light  and  trolley  wires  a,re  left 
without  a  covering. 

Moist  air,  all  wet  substances  and  water,  are 
excellent  conductors,  and  by  one  of  the  principal 
laws  of  electricity  an  electric  current  returns  to 
its  source  by  the  easiest  possible  path,  or  along 
the  line  of  least  resistance. 


312  ELECTRIC    WIRING 

The  ground,  whether  earth  or  lake  or  sea,  is 
always  ready  to  serve  as  the  easiest  and  shortest 
path  back  to  the  source,  and  in  order  to  have  the 
current  flow  through  all  the  wires  of  the  circuit  in 
undiminished  force,  and  to  provide  against  any 
portion  of  it  taking  a  short  circuit,  the  wires 
exposed  to  possible  dampness,  contact  with  water, 
or  the  like,  are  insulated,  that  is,  they  are  covered 
with  a  dampness-proof,  water-proof,  non-con- 
ducting material. 

Such  materials  are  glass,  ebonite,  paraffin, 
shellac,  india  rubber,  gutta  percha,  sulphur,  silk, 
porcelain,  etc  Some  of  these  are  suitable  in  some 
places  and  conditions,  and  others  in  others. 

Iron  and  porcelain  are  used  for  supporting  bare 
wires.  For  telegraph  cables  gutta  percha  is  used, 
which,  however,  is  easily  affected  by  heat,  and 
cannot  be  used  for  insulating  electric  light  wires 
carrying  a  large  voltage.  Instead,  a  fibrous 
matter  (jute  and  the  like),  steeped  in  a  resinous  or 
bituminous  compound,  is  used.  India  rubber 
(vulcanized  to  make  it  harder  and  more  durable) 
is  considered  the  best  insulator  for  house  wiring. 

To  prevent  decomposition  of  the  rubber  by  the 
copper,  the  copper  wire  is  usually  ccj. .  ~ 
which  also  makes  soldering  the  joints  easier. 
Then  a  cover  of  india  rubber  is  put  on,  then  a 
second  cover  of  vulcanized  india  rubber.  The 
third  covering  consists  of  india-rubber-coated 


ELECTRIC    WIRING  313 

tape    ( okonite ),    and    over    this    tarred    flax    is 
braided  and  coated  with  a  preservative  compound. 

When  the  wire  is  so  insulated,  the  electric  cur- 
rent finds  it  easier  to  travel  the  length  of  it  foi 
thousands  of  miles  than  to  escape  through  the 
insulation,  one-sixteenth  or  one-eighth  of  an  inch 
thick.  But  remember,  wherever  the  insulation  is 
faulty  or  injured,  admitting  water  or  contact  with 
any  other  good  conductor,  there  the  current  escapes 
and  returns  by  the  shortest  route  to  the  source. 

Aside  from  the  loss  in  lighting  power,  such 
defects  are  frequently  the  cause  of  disastrous 
conflagrations  or  of  death.  House  wiring  should 
be  entrusted  to  experienced,  skillful  and  con- 
scientious men  only. 

For  test  of  insulation,  see  page  281. 
SIZE  OF  WIR,E 

Two  considerations  determine  the  proper  size  of 
wire  to  be  used  in  a  circuit:  The  wire  must  be 
thick  enough  to  carry  an  electric  current  of  the 
desired  voltage  at  the  desired  rate  of  flow,  and  on 
the  other  hand,  to  avoid  unnecessary  expense,  it 
must  not  be  thicker  than  necessary. 

If  the  wire  is  too  thin,  a  portion  of  the  current  is 
converted  into  heat  (see  page  309),  and  the  hot 
wire  becomes  a  source  of  great  danger.  The  fire 
insurance  inspectors  insist  on  this  point,  and 
rightly  so.  Of  course,  the  light  furnished  by  too 
thin  a  wire  is  very  poor. 


314  ELECTRIC    WIRING 

CONNECTIONS 

A  joint  or  connection  must  be  solid,  that  is,  it 
must  not  offer  any  more  resistance  than  the  wire 
itself,  and  must,  therefore,  be  made  with  the 
utmost  care.  The  second  requirement  is,  it  must 
be  damp  proof. 

The  strands  of  copper  are  first  cleaned  by  scrap- 
ing, then  interlapped  or  scarfed,  another  wire  is 
wound  around  the  joint  (especially  in  the  case  of 


Joints. 


large  cables),  and  the  whole  is  soldered.  This 
gives  a  so-called  hard  joint.  Then  insulation  is 
put  on  with  equal  care,  first  india  rubber,  and 
then  okonite  (india  rubber  tape),  making  a  solid 
and  dampness-proof  insulation. 

ARRANGEMENT   OF    CIRCUITS 

The  plan  for  the  wiring  of  a  building  should  be 
given  great  care  and  skill,  requiring  much  experi- 
ence. 

v  First,  find  the  point  at  which  the  main  circuit 
from  the  dynamo  or  supply-wire  will  be  most 
conveniently  divided  up  into  a  number  of  smaller 
circuits.  A  fault  is  easily  located  in  a  small  circuit 
and  cannot  disturb  the  service  except  in  its  own 
circuit.  A  "central  distribution  board"  is 
erected,  and  from  this  a  small  special  circuit  leads 


ELECTRIC    WIRING  315 

to  each  lamp,  or,  in  a  large  building,  cables  run  to 
a  number  of  branch  distribution  boards,  with  which 
then  the  lamps  are  connected. 

It  is  best  to  connect  each  lamp  with  the  distribu- 
tion board  by  two  wires  (parallel  wiring).  If  all 
the  lamps  are  strung  along  one  common  circuit 
(series  wiring),  all  the  lamps  will  be  affected  by 
any  little  irregularity,  and  the  distribution  of  cur- 
rent is  uneven.  These  disadvantages  far  outweigh 
the  saving  in  the*  first  expense  of  installation. 

PLACING   THE   WIRES 

The  greatest  care  should  be  taken  to  keep  the 
wires  absolutely  free  from  dampness  or  water, 
since  they  establish  at  once  a  short  circuit  (earth, 
ground,  leakage),  and  a  portion  or  all  of  the 
electric  current  returns  by  the  nearest  path  (by 
wall  or  pipe,  or  the  like,  and  the  ground)  to  the 
source. 

Another  great  cause  of  annoyance  to  be  guarded 
against,  is  a  short  circuit  by  leakage  from  one  wire 
to  another  through  defective  insulation,  crossed 
wires,  etc.  The  electric  current,  finding  its  way 
through  dry  dust,  lint,  rubbish,  or  wooden  parts, 
heats  them  to  the  point  of  ignition,  and  a  fire  is 
the  result. 

In  placing  the  wires,  neatness  of  appearance, 
safety  from  leakage,  and  protection  from  fire  are 
the  three  points  to  be  kept  in  mind. 


316  ELECTRIC    WIRING 

Wires  without  casings  should  be  6  inches  apart 
for  mains,  and  2%  inches  for  smaller  sizes. 

Metal  or  glass  tubing  is  a  good  protection 
against  gnawing  rats  or  mice,  but  insurance 
inspectors  do  not  look  upon  them  with  favor  for 
high-voltage  circuits. 

The  most  serviceable  casings  are  of  well- 
seasoned  hard  wood,  grooved.  The  fillets  sepa- 
rating the  grooves  should  be  i%  inches  in  width  for 
mains,  i  inch  for  main  branches,  y2  inch  for 
smaller  branches.  The  inside  of  wood  casings 
should  be  painted  with  a  fire-proof  paint  or  com- 
pound, and  the  wires  packed  in  with  asbestos  or 
silicate  cotton. 

For  chandeliers  twin  wires  are  generally  used. 
They    should    be    handled    very    carefully,    and 
properly  protected  with  cut-outs. 
CUT-OUTS 

What  the  safety-valve  is  for  the  boiler,  the  cut- 
out or  safety-fuse  is  for  the  electric  circuit.  It 
consists  of  a  short  lead  or  tin  wire  of  a  siae  propor- 
tionate to  the  greatest  quantity  of  current  required 
for  the  circuit.  If  the  current  increases  beyond 
that  point,  the  tin  or  lead  wire,  unable  to  transmit 
more  than  so  much  of  the  current,  converts  the 
excess  into  heat  and  melts  (is  blown),  thus  break- 
ing the  circuit. 

The  cut-out  is  a  guarantee,  therefore,  against 
overloading  the  wire  from  any  cause,  short  circuit, 


ELECTRIC    WIRING  317 

crossing  wires,  or  negligence  of  dynamo  attendant. 
The  best  place  for  the  cut-outs  is  on  the  distribu- 
tion board,  where  the  small  circuits  are  connected 
to  the  mains.  The  circuits  can  thus  be  easily 
disconnected  by  removing  the  safety-fuse.  For 
special  purposes  cut-outs  are""  placed  wherever 
desirable. 

THE    SOCKETS 

Incandescent  lamps  receive  the  current  from 
contact  pieces  in  the  socket  of  the  "shoe,"  or 
'  'plug, "  or  in  a  socket  swinging  on  the  circuit  wires. 

Such  plugs  are  frequently  distributed  along  the 
walls  of  the  rooms,  for  the  sake  of  attaching  a 
portable  lamp  to  either  one  of  them,  wherever  it 
may  become  desirable.  This  is  a  great  con- 
venience. 

The  socket  is  either  a  screw  socket  or  a  "bayo- 
net" socket.  The  latter  is  simply  pushed  in  and 
turned  around  one-eighth,  to  make  connection 
with  the  circuit.  In  the  screw  socket  connection 
does  not  take  place  until  the  lamp  is  screwed  in  as 
far  as  it  will  go. 

To  avoid  the  handling  of  the  lamps  when  the 
current  is  to  be  turned  on  or  off,  a  key  or  switch  is 
provided.  This  key  should  never  be  placed  any- 
where between  full-off  and  full-on,  not  even  for  a 
moment,  because  in  a  partial  connection  the  con- 
tact pieces  will  get  heated  and  grave  consequences 
may  result  at  once  or  later  on. 


THE  ELEMENTS  OF  ALGEBRA 

BY  PROF.  O.  H.  L,  SCHWETZKY 

Q.— What  is  arithmetic? 

A. — The  science  of  numbers,  or  the  science  of 
numerical  equivalents. 

Q.— What  does  it  teach? 

A. — It  teaches  how  to  calculate  or  compute 
quantities  by  the  means  of  numbers. 

Q. — What  is  algebra? 

A. — Sir  Isaac  Newton  called  it  "universal 
arithmetic,"  meaning  by  this  term,  that  algebra 
teaches  the  rules  which  apply  to  any  and  all 
numbers. 

Q. — What  is  one  of  the  principal  differences 
between  arithmetic  and  algebra? 

A. — In  arithmetic  we  have  only  10  characters 
with  which  to  work:  o,  i,  2,  3,  4,  5,  6,  7,  8,  9 — 
and  which,  besides,  have  a  limited  meaning, 
variable  by  position  only.  In  algebra,  quantities 
of  every  kind  may  be  denoted  by  any  characters 
whatever. 

Q. — -What  are  the  characters  mostly  used  in 
algebra? 

A. — The  known  quantities  in  each  case  are 
generally  denoted  by  the  first  letters  of  the 
318 


THE  ELEMENTS  OF  ALGEBRA     319 

alphabet,  a,  b,  cy  etc. ,  and  the  unknown  quantities 
to  be  found  are  represented  by  the  last  letters  of 
the  alphabet,  z,y,  x,  w,  etc. 

Q. — What  do  these  characters  represent? 

A. — They  represent  any  number  chosen. 

If  we  assume  a  to  represent-g,  and  b  to  repre- 
sent 3,  then  a-|-b=i2;  and  in  a  +  b  =  c  we 
would  put  c  =  12, 

In  a  —  b  =  c  we  would  have  c  =  6 ;  inaXb  =  c, 
c  would  be  =27;  in  a-r-b  =  c,  c  would  be 
=  3- 

In  a  -r-  b  =  c  -5-  x,  x  is  the  required  answer,  a,  b 
and  c  being  known  quantities. 

Q. — What  signs  are  used  in  arithmetic? 

A. — Plus  (-(-)  for  addition,  minus  ( — )  for  sub- 
traction, times  (X)  for  multiplication,  by  (-*-)  for 
division,  and  equals  (=)  to  show  equality. 

Q. — What  signs  are  used  in  algebra? 

A. )-,  —  and  =,  as  in  arithmetic.     The  X  is 

rarely  used.     Instead  of  a  X  b  the  form  a  b  is  em- 

a 
ployed,  or  a  .  b  .     Instead  of  a  -r-  b  we  write  e- 

Q. — Name  another  difference. 

A. — In  arithmetic  any  operation  that  is  readily 
performed  is  at  once  executed  and  the  result 'sub- 
stituted, as  10  for  7  +  3,  3  for  10  —  7,  21  for  3X7, 
7  for  21-7-3;  but  in  algebra  this  is  not  done :  a  -\-  b 
is  called  a  sum ;  a  —  b  is  a  quantity  equal  to  the 
excess  of  a  over  b ;  a  b  is  a  product ;  r-  is  a  quotient ; 
(a  +  b)  (c  +  d)  is  the  product  of  the  two  sums 


320  QUESTIONS    AND    ANSWERS 

a  -f-  b  and  c  +  d  ;  a  (b  -\-  c)  is  the  product  of  a  and 
the  sum  b  +  c  ;  a  (  —  J  is  the  product  of  a  and  the 

quotient  —  ,  etc. 

c 
Q.  —  Explain    the    use   of    the    parenthesis,    (), 

further? 

A.  —  It  means  that  the  term  enclosed  in  the 
parenthesis  is  to  be  treated  as  one  quantity.  If 
a  =  9,  b  =  8,  c  —  4,  and  d  —  3,  then  (a+b)  (c+d) 
=(9  +  8)  (4  +  3)  =  17  X  7=H9;  a(b  +  c)  =  9X  12 
=  108  ;  a  (  —  J  =  9  X  2  =  1  8. 

Q.  —  Are  there  no  definite  numbers  used  in 
algebra? 

A.  —  Yes.  a-|-ais  written  2  a;  ab  +  ab-}-ab  = 
3  ab,  etc.  The  definite  numbers  in  this  case  are 
called  numerical  coefficients,  or  for  short,  co- 
efficients. 

a  X  a  is  written  a  a  or  a2,  which  is  read  '  '  a 
square."  a  X  a  X  a  is  written  a3,  which  is  read 
"a  cube,"  etc.  In  this  case  the  figure  indicates 
how  many  times  a  quantity  is  to  be  multiplied  by 
itself,  and  is  called  the  exponent. 

Q.  —  In  what  relation  does  a  stand  to  a2  ? 

A.  —  It  is  the  square  root  of  a2. 

Q.  —  What    is    the    meaning    of    a  —  ^  "t"  if"-*  J 


A.  —  That  depends  on  the  definite  numbers  to  be 
substituted  for  the  characters.  If  all  the  +  quan- 
tities (positive  quantities),  a+(-?J  +  6ac  added 


THE    ELEMENTS    OF    ALGEBRA  32! 

together  give  a  larger  quantity  than  the  —  quanti- 
ties (negative  quantities),  b  +  2  ab  -j-  d  added  to- 
gether, then  the  answer  is  positive,  otherwise  it 
will  be  negative. 

Q. — How  can  a  quantity  be  negative? 

A. — In  the  case  of  bookkeeping  it  would  mean 
that  there  is  that  much  deficit  or  loss ;  in  traveling 
it  would  indicate  that  distance  back  of  a  certain 
point  instead  of  forward;  on  a  thermometer  or 
steam  gauge  it  would  indicate  so  many  degrees 
below  zero  instead  of  above,  etc.  Plus  means 
"above  zero,"  or  "more  than  nothing,"  minus 
means  "  below  zero,"  or  "  less  than  nothing." 

Q. — What  is  the  difference  between  a  —  b  +  c 
and  a  —  (b  +  c)  ? 

A. — In  the  first  case  b  is  to  be  subtracted  from 
the  sum  of  a  and  c ;  in  the  second  case  the  sum  of 
b  and  c  is  to  be  subtracted  from  a.  The  difference 
becomes  clear  by  substituting  definite  numbers: 
20  —  9+4  =  15;  20  —  (9  +  4)  =  7- 

Q. — What  is  the  meaning  of  a  —  (b  +  c)  =  a — 
b  — c? 

A. — It  means  that  additions  and  subtractions 
may  be  performed  in  any  order.  We  may  either 
subtract  the  sum  b+c  from  a,  or  we  may  subtract 
first  b  from  a  and  then  subtract  c  from  the 
remainder.  The  result  is  the  same. 

Q. — Can  you  further  illustrate  the  meaning  of 
the  minus  sign  ? 


322  QUESTIONS    AND    ANSWERS 

A. —  i.     a-|-b  =  c —  b 

a  +  2/b  =  c 

Taking  —  b  away  on  one  side  is  the  same  as 
adding  +b,  because  -f-b—  b  —  o.  To  keep  the 
two  terms  at  the  sides  of  the  =  sign  of  the  same 
value,  we  must  add  -|-  b  at  the  other  side,  too, 
which  gives  2  b. 

2.     a  ( —  b)  =  —  ab 

This  signifies  that  "  multiplication  by  a  negative 
quantity"  ( — b)  means  "starting  from  the  zero 
point  in  the  opposite  direction."  If  John  has 
$500  assets,  and  Frank  has  ten  times  as  much 
liabilities,  he  owes  $5000.  Also:  If  John  owes 
$500,  ( —  a),  and  Frank  owes  ten  (b)  times  as 
much,  he  owes  ( —  a)  b  =  —  ab,  or  $5000. 
3.  (-a)(-b)  =  +ab 

This  is  the  reverse  of  the  above  (2).  The  same 
principle  applies.  If  John  is  $500  short,  and  Fred 
has  ten  times  as  large  an  amount  of  cash  on 
hand,  he  has  $5,000.  Expressed  as  a  rule,  this 
simple  truth  presents  itself  as  follows: 

Minus  multiplied  by  minus  produces  plus, 

or,  in  other  words,  the  product  of  2  negative 
factors  is  positive. 

Q. — Can  you  further  illustrate  this  rule? 

A. — i.  A  rich  man  said  to  his  son:  "I  will 
make  you  the  owner  of  a  fortune  8  times  as  large 
as  your  present  indebtedness."  The  son  con- 


THE  ELEMENTS  OF  ALGEBRA     323 

fessed  that  he  owed  at  that  moment  $7,000.  To 
make  good  his  promise,  the  father  had  to  pay  the 
debt  and  give  his  son  $56,000  besides. 

2.  One  ship  sailed  200  miles  due  east  from  a 
port,  while  another  steamed  3   times  as  far  due 
west.     They  were  consequently  800  miles  apart, 
one  being  200,  and  the  other  600  miles,  from  the 
port,  in  opposite  directions. 

3.  An  open  siphon,  one  arm  o'f  which  had  a  five 
times  larger  inside  area  of  cross-section  than  the 
other,  was  provided  with  a  scale,  and  filled  with 
water  to  the  zero  point  of  the  scale.    A  piston  was 
introduced  in  the  wider  arm,  and  pressed  down, 
until  the  water  surface  in  this  wider  arm  stood  at 
3  inches  below  zero.     Where  was  the  surface  in 
the  other,  smaller  arm?    Ans.  ( — 3)  ( — 5)  =  -f-  15. 

Q. — What  is  the  meaning  of  a(  —  j  =  —  ? 

A. — It  means  that  multiplications  and  divisions 
may  be  performed  in  any  order. 

Q. — What  advantage  does  algebra  give? 

A. — It  gives  short  characters  instead  of  long 
numbers,  and  tedious  multiplications,  etc.,  are 
avoided,  as  no  such  operations  need  to  be 
executed,  except  in  the  answer,  where  the  given 
values  are  substituted. 


THE  TRACTION  ENGINE 

A  traction  engine  is  a  locomotive  for  common 
roads,  and  by  throwing  the  driving  wheels  out  of 
gear  is  converted  into  a  stationary  engine. 


As  a  traction  engine  it  is  steered  by  a  worm 
gearing,  which  turns  a  winding  shaft,  on  which  a 
chain  is  wound  and  unwound,  drawing  one  or  the 
other  front  wheel  back,  according  to  the  direction 
in  which  the  engine  is  to  run.  The  engineer  steers 
by  turning  a  hand-wheel  controlling  the  worm 
gearing. 

The  driving  wheels  have  V-shaped  projections 
on  their  rims  to  prevent  slipping.  They  get  their 
motion  through  differential  or  compensating  gears 
from  the  engine.  (See  cut  page  326.)  The  motion 
of  the  engine  is  reversed  through  a  special  device, 
a  single  eccentric  reversing  gear,  or  through  a 
reversing  rack.  (See  pages  330,  331). 


THE    TRACTION    ENGINE 


325 


Coal  and  water  are  carried  in  the  combination 
tank. 


For  turning  the  curves  of  a  road  one  of  the 
drivers  is  loose  on  the  shaft,  so  that  it  may  run  a 
longer  or  shorter  distance  than  the  other  driver, 
without  straining  the  axle  or  connections.  For 
running  on  a  straight  road,  the  loose  driver  is 
made  solid  with  the 
shaft  by  inserting  the 
key  A  into  slot  B. 

As  a  stationary 
engine  (the  drivers 
being  thrown  out  of 
gear),  the  pulley-  A». 
face  fly-wheel  (or  a 
friction  clutch  wheel, 
see  page  326),  fur- 
nishes the  power  by 
means  of  a  belt. 

The  rear  axles  and 
brackets  of  all  good 
traction  engines  are 
placed  back  of  the  firebox,  so  that  the*  weight 
will  be  well  distributed  between  the  fore  and 
aft  wheels.  Short  axles  riveted  to  the  sides  of 
the  firebox  are  very  dangerous. 

DIFFERENTIAL  OR  COMPENSATING  GEAR 

The     differential     or     compensating     gear     is 
arranged  as  seen  in  the  cut:  A  is  a  large  bevel 


THE    TRACTION    ENGINE 


wheel    (loosely  set  on  the   axle),  carrying  three 
pinions,    B,    so     distributed    over    it    that    they 

together  engage 
the  ground  wheel 
by  meshing  either 
with  C  or  D,  ac- 
cording as  the 
engine  is  to  travel 
forward  or  b  a  c  k- 
ward.  C  is  bolted 
to  the  main  drive- 
wheel  ;  D  is  keyed 
on  t  h  e  axle.  A 
gets  its  motion 
from  the  engine 
through  the  in- 
clined shaft  and  the 
bevel  pinion,  E. 


FRICTION-CLUTCH    FLY-WHEEL 

The  fly-wheel  of  a  traction  engine  must  allow  of 
being  thrown  in  and  out  of  gear  easily.  One  of 
the  most  convenient  de- 
vices for  this  purpose  is 
the  friction  clutch  shown 
in  the  cut. 

The  wheel  has  diam- 
etrically placed  a  driving- 
arm,  A,  to  which  is  cast  a 
sleeve,  B,  surrounding 
the  axle  of  the  wheel. 
The  end  of  B  carries  the 
pinion  C,  keyed  to  it  at 
D.  Both  ends  of  the  driv- 
ing arm  A  Have  a  cast- 
iron  shoe,  E,  loosely 
bolted  to  them.  The  bolts 
are  solid  with  A.  These 
shoes  are  hollow  and 
rilled  WT  i  t  h  hard  -  wood 
blocks  with  a  surface  curved  to  correspond 
exactly  with  the  inside  surface  of  the  wheel  rim, 


THE    TRACTION    ENGINE  327 

turned  true.  The  free  ends  of  the  shoes  are  pro- 
vided with  a  toggle-joint  (or  turn  buckle  joint), 
G,  G,  by  which  the  wood  is  pressed  firmly  against 
the  wheel  rim,  when  the  fly-wheel  is  to  be 
engaged.  The  toggle-joint  is  worked  by  throwing 
the  collar  F,  which  loosely  fits  around  the  sleeve 
B,  toward  the  wheel.  This  is  done  by  means  of  a 
lever  within  easy  reach  of  the  engineer,  but  not 
shown  in  the  cut. 

CROSS-HEAD 

A  is  the  piston  rod  with  threaded  end.  B  is  the 
piston  lock-nut,  C  is  the  cross-head  frame.  D,  D 
are  the  slide  blocks,  E,E  are  the  cap  screws  which 
hold  the  slippers  (slides),  D,  D,  to  the  cross-head 
frame.  F,  F  are  the  adjusting  screws  for  taking 
up  the  wear  of  the  slides.  This  is  done  (about 
once  a  year)  by  slightly  slacking  out  the  bolts  E, 
E,  and  screwing  in  the  screws  F,  F,  until  the  lost 


motion  is  taken  up.  G  is  the  small  end  of  the  con- 
necting rod  containing  the  brasses,  adjustable  by 
means  of  a  screw  bolt,  H,  engaging  with  a 
beveled  block  in  the  strap,  said  bolt  being  locked 
in  position  by  jam-nut  K.  The  cross-head  pin,  L, 
can  be  removed  by  unscrewing  the  nut  from  the 
pin  and  driving  the  pin  out  of  the  cross-head  frame 
by  means  of  a  hammer  and  a  wooden  block. 


328 


THE    TRACTION    ENGINE 


DIMENSIONS  AND  HORSE-POWER  OF  TRACTION  ENGINES 

Their  speed  is  about  250  revolutions  a  minute. 


Ten-inch  Stroke 
Simple  High-Pressure 
Engine. 

Ten-inch-Stroke  Compound 
Tandem. 

Horse 

Diameter 

Horse 

Diameter  in  inches. 

Power. 

in  inches. 

Power. 

HighP.Cyl. 

L/ow  P.  Cyl. 

9 

7X 

12 

$X 

8X 

12 

8X 

15 

6^ 

9 

15 

9 

20 

7 

10 

20 

10 

25 

7% 

n 

TANDEM     COMPOUND     CYLINDERS    AND    VALVE 
MOTION 

The  Tandem  Compound  Traction  Engine  does 
not  differ  much  from  the  plain  single  cylinder 
engine,  in  operation,  or  in  the  care  it  requires. 
Where  the  work  (load)  amounts  to  the  full  horse- 
power capacity  of  the  engine,  the  tandem  com- 
pound is  economical,  otherwise  it  is  wasteful. 

The  accompanying  cut  shows  the  very  simple 
and  compact  arrangement  of  the  two  cylinders 
(one  high  and  one  low  pressure)  and  the  slide 
valve.  The  cylinders  are  cast  separately  and 
bolted  together  at  U.  The  partition  R  is  cylinder 
head  for  both  cylinders,  is  held  in  place  by  jam 
bolts  (Y),  and  at  S  the  piston  rod  passes  through 
its  center.  The  packing  is  metallic  ^and  does  not 
need  adjustment  or  renewal.  One  piston  rod 
carries  the  two  pistons,  A,  B.  By  unbolting  at  U,  U, 
the  interior  of  the  two  cylinders  is  reached  easily. 

Only  on  the  larger  or  "low  pressure"  cylinder  is 
there  a  steam  chest,  valve  seat,  etc.  In  order  to 
connect  with  both  cylinders,  the  slide  valve  and 
seat  are  arranged  as  follows :  Steam  for  the  boiler 
enters  through  H  into  X,  a  chamber  formed  by  the 
hood  enclosing  the  slide  valve.  This  hood  and  the 
slide  valve  proper  are  one  casting,  and  move 


THE    TRACTION    ENGINE 


329 


together  in  the  steam  chest,  M.  The  passages  I, 
I  communicate  with  M.  From  X  the  live  steam 
passes  through  L  into  E  in  the  high-pressure 
cylinder.  At  the  end  of  the  stroke,  X  and  K  com- 
municate and  live  steam  enters  from  X  through 
K  (see  dotted  lines)  into  D  at  the  other  end  of  the 
high-pressure  cylinder,  reversing  the  piston 
motion.  The  expanded  staam  in  E  exhausts 
through  L  into  the  receiving  chamber,  M,  and 
from  there  passes  through  I  and  N  into  G  in  the 
low-pressure  cylinder.  The  steam  expanded  in 
D  exhausts  through  K  into  M,  and  passes  from 


there  through  I,  P  into  F.  P  and  N  finally  carry 
the  steam  exhausted  from  the  low-pressure 
cylinder  off  through  O.  Port  J  in  M  serves  to 
admit  live  steam  to  facilitate  starting  the  engine. 
After  starting,  it  is  closed. 

The  low-pressure  cylinder  must  be  larger  than 
the  high-pressure  cylinder,  because  the  expanded 
steam,  exhausting  from  the  latter  into  the  former, 
is  so  much  weaker  than  live  steam  that  it  requires 
more  piston  area  'to  work  on,  to  furnish  the  same 
pressure  as  the  live  steam  exerts  on  the  smaller 
piston  area.  The  proportion  of  the  areas  is  closely 
culiulated  by  experts;  roughly  it  maybe  said  to 
be  1:2.  See  table,  page  328, 

For  more  explicit  information  on  compound  and 
pther  engines  see  pages  96,  104  and  133. 


330  THE    TRACTION    ENGINE 

Some  engineers  have  asked  why  the  valve  was 
not  worked  directly  by  the  piston  rod,  by  means  of 
a  lever  of  the  proper  kind  and  proportion.  (See 
leverage,  page  241.)  In  the  beginning  the  valve 
was  worked  in  that  crude  way,  and,  at  the  very 
first,  by  hand.  The  necessity  of  economy,  how- 
ever, in  the  consumption  of  steam  has  led  to  the 
devising  of  eccentrics,  link  motion,  compound 
engine,  single  eccentric,  etc. 

SINGLE   ECCENTRIC,    VALVE  AND   ENGINE 
REVERSING    GEAR 

For  general  information  about  the  eccentric,  see 
page  116;  link  motion,  page  144. 

A  traction  engine  must  necessarily  have  the 
most  simple  possible  attachments.  A  very  simple 
and  ingenious  valve  and  reversing  gear  is  shown 
in  the  cut. 

There  is  only  one  eccentric.  To  the  eccentric 
strap,  which  carries  the  valve  rod,  a  roller  is 
pivoted  a  little  above  the  valve  rod  pin.  The 
roller  runs  in  a  guide, 
the  position  of  which 
is  regulated  by  the  re- 
verse lever,  to  which 
it  is  connected  by  a 
"reach  rod."  Chang- 
ing the  angle  of  the 
guide  reverses  the  en- 
gine, or  it  may  simply 
shorten  or  lengthen 
the  travel  of  the  valve 
and  thereby  change 
the  point  at  which  the 
steam  is  "cut  off." 

Besides  its  extreme 
simplicity,  this  device 
has  the  further  great 
advantage  that  it 
makes  the  lead  of  the 
valve  "constant,"  that  is  to  say,  the  lead  does 
not  vary  with  the  travel,  as  it  does  in  link  motion. 
The  valve  gives  a  quick,  full  opening  at  exactly 


THE    TRACTION    ENGINE  331 

the  right  moment,  admitting  steam  promptly  at 
the  dead  points.  Also,  it  cuts  off  quickly,  giv- 
ing quick  expansion. 

To  reverse,  the  lever  is  thrown  back  to  the 
furthest  notch  on  the  quadrant.  To  stop,  the 
lever  is  placed  in  the  center  notch. 

By  holding  the  lever  between  the  center  notch 
and  one  of  the  other  notches,  the  stroke  of  the 
slide  valve  may  be  set  at  any  aesired  length  short 
of  its  extreme  travel.  This  is  done  by  economical 
engineers,  when  the  load  is  light 

The  whole  gear  is  so  simple  and  durable  that  no 
skill  is  required  to  run  it,  or  to  replace  and  adjust 
it.  The  eccentric  has  its  center  almost  directly 
opposite  the  crank  pin,  so  that  the  roller  will  stand 
exactly  over  the  center  of  the  guide,  when  the 
engine  is  at  either  dead  center.  This  renders  it 
easy  to  find  the  correct  position  of  the  eccentric. 

To  set  the  valve,  the  eccentric  rod  is  then 
adjusted  so  as  to  give  equal  lead  at  both  ends  of 
the  valve. 

REVERSING    RACK 

For  throwing  the  eccentric  into  the  reverse 
position,  the  reversing  rack  shown  in  the  accom- 


panying cut  is  used  on  simple  or  single  cylinder 
engines.  Where  the  eccentric  is  cut  away  in  the 
cut,  the  arrow  shows  the  reversing  rack. 


332  THE    TRACTION    ENGINE 

STACKER   GEARING   ANDi  TURNTABLE 

A,  A  is  the  upper  frame;  B,  B  is  the  lower 
frame.  C  is  the  lower  frame  chair  bracket,  with  a 
central  hub,  and  the  pocket  D,  in  which  a  collar 
turns,  that  is  attached  to  the  upper  frame  chair 
bracket  E.  The  center  gear  shaft  turns  in  the 
lower  frame  hub  and  in  the  upper  frame  collar, 


and  is  geared  below  (miter  gear  F)  to  the  main 
shaft,  G,  driven  by  pulley  H,  and  above  (miter 
gear  I,  K)  to  the  sprocket  wheel  shaft  L.  M  is  the 
shaft  box.  N  is  the  bracket  for  the  pin  which,  by 
means  of  the  lever  O,  serves  to  clutch  the  three- 
wheel  gear  P,  P,  P,  with  the  main  shaft  G,  around 
which  it  fits  loosely.  When  so  engaged  the  pinion 
Q  at  the  other  end  of  the  sleeve  engages  pinion  R 
and  the  shaft  S,  at  the  other  end  of  which  there  is 


THE   TRACTION    ENGINE  333 

a  bevel  spur  wheel,  T,  driving  U  and  V  in  opposite 
directions.  The  reversing  spool,  W,  serves  to 
throw  shaft  X  into  gear  with  either  U  or  V.  W  is 
worked  by  means  of  the  lever  Y.  Z  is  a  universal 
joint,  enabling  shaft  a  and  worm  b  to  be  thrown 
out  of  gear  with  the  turntable  d  by  the  lever  c. 
The  turntable  d  is  attached  to  A,  A,  pivots  around 
the  central  shaft  in  the  collar  in  D,  and  has  a  ball- 


bearing, E,  E,  attached  to  the  lower  frame.  The 
shaft  L  drives  the  working  shaft /"by  means  of  the 
sprocket  wheels  g,  g,  h,  h.  The  three  pulleys  on 
shaft/ drive  the  different  parts  by  belting. 

Lever  O  starts  or  stops  the  stacker;  lever  c 
starts  or  stops  the  turntable  d;  lever  Y  controls 
the  direction  in  which  d  turns.  When  the  turn- 
table is  thrown  out  of  gear  the  stacker  may  be 
swung  around  by  hand. 


334 


THE    TRACTION    ENGINE 


THE    STACKER 

The  cuts  show  a  straw 
stacker,  both  folded  and  in 
operation.  The  folding  and 
unfolding  are  done  by  hand 
or  steam  power. 

A  carrier,  24  feet  long, 
delivers  the  straw  from  the 
hopper  of  the 
threshing  ma- 
chin  e  to  the 
stacker.  The 
stacker  carries 
the  straw  to 
the  desired 
height  and 
dumps  it  on 
the  stack. 


The  mechanism  of  the  turntable,  reversing  gear, 
etc.,  are  fully  described  on  pages  332,  333. 


JOURNAL-BOX    BABBITTING 


335 


*.-? 

"a  V 

u 

0 

Standard  Babbitts 

£M 

u 

P. 

^; 

c3g 

a 
o 

a 

a 

a 

•^ 

* 

U 

H 

N 

H 

High  Speed  Babbitt... 

IO 

16 

^ 

70 

IOO 

Medium  or  Common... 

4 

6 

QO 

IOO 

Machinery  Bearings... 

£8 

12 

IOC 

Muntz  Metal  . 

60 

/in 

IOO 

German  Silver  

33  '/ 

•20  I/ 

IOO 

White  Brass  

IO 

IO 

80 

IOO 

Fine  Yellow  Brass  

66 

34 

IOO 

Gun  Metal  for  Valves, 

etc  

90 

IO 

IOO 

Journal    Brasses    for 

Rods    etc  

80 

17^ 

2  // 

IOO 

In  melting  babbitt  metal  care  must  be  taken 
not  to  burn  it  by  overheating.  Melt  a  part  first 
in  small  chunks,  and  add  remainder  gradually. 
As  soon  as  all  melted,  remove  from  fire  and  skim 
off  the  dirt.  If  heated  beyond  the  melting  point 
the  softer  components  evaporate  and  leave  the 
mass  in  a  pasty  condition. 

When  about  to  babbitt  a  journal  wrap  one 
thickness  of  common  writing-paper  smoothly 
around  the  bearing,  fastening  it  in  place  with 
twine  wound  around  in  a  regular  spiral  line  three- 
sixteenths  of  an  inch  apart.  The  paper  keeps  the 
babbitt  from  getting  chilled  by  the  journal. 
It  will,  therefore,  have  a  fine  surface,  and  will 
also  fit  just  right  without  any  scraping.  The 
twine  leaves  nice  oil  grooves. 

Before  pouring  the  metal  through  the  t>il-hole, 
make  sure  the  journal  is  level  and  in  central  posi- 
tion. By  means  of  two  pasteboard  rings  fitting 
the  journal,  the  ends  of  the  box  are  closed,  using 
putty  or  soft  clay.  A  high  funnel  of  clay^  is  made 
around  the  oil-hole  to  facilitate  the  pouring  in  of 
the  babbitt,  and  to  increase  the  pressure,  so  as  to 
have  the  babbitt  fill  the  box  perfectly. 


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